From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4159525A2DD; Thu, 16 Apr 2026 10:16:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334614; cv=none; b=DYl/PTwmrVqDChUU52IayH3PjORTXFMPaDQtMDS5oaOMbxWJsPpKWJv+K/C4sPr9dOzsQvVVFmCHtdAhzUg5qf7HQFpc42f8x6zt6Ml9YUSLlTTL0aBUdNF7NXXimbo7/ySTykYkJ3KU26OqimdNPp8ew20E3zxJ1sZvq7r1vZQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334614; c=relaxed/simple; bh=rqs+M1PyAlmYt6BIh4c8u/Ci2zxPhYMYAfWmhLkdOIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Clw8ZbBdk2juTZkO9UmAVO6xqQ861FRpTpLRSNAZDsBI7ftDdyx7bnorH4WEIhmo1eS/3PSbqQAwUTEqu4JUUuKRQnmXNrvyZL4VIeTItC5/har+l9ZXjPsUBikcFJHtq6RiXXblIs7fyoaEG2Z35SGwwxyeMtTYyFgirQhHRpk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MlL6Monw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MlL6Monw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 365CEC2BCAF; Thu, 16 Apr 2026 10:16:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334614; bh=rqs+M1PyAlmYt6BIh4c8u/Ci2zxPhYMYAfWmhLkdOIg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MlL6MonwIdPIKZGJrkNAXqg2rC+y1M0wlEkNC6rkHkwz8wU5lNTSxJAkG1/DrEutx fmjuz4GtFb7phepFE/0ch6R0Yq0UnNumseGvqv8NLs8JuM779OXZzw16ZN31xLdDd6 v/RfCmd+QgTaF0g/Cd+S+lIH4HQIhoRPkKgelQYb+wiCGk6dI4zUVRItajvaCJq8WH CFCZQv4Cf0hpREuYBTbgIL0cnq0c+d0ixbil7zjGRuJiOM1+4+htMK6O1yfXP8/Q7q CPx2e8nyGTql8i6k00xNbilgxz/SX0AZM98DFYtdIZpk8xG5GBmPjwioI/aWX7OvpK hiJXI6Aw4RrDw== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 1/8] tracing/fprobe: Reject registration of a registered fprobe before init Date: Thu, 16 Apr 2026 19:16:51 +0900 Message-ID: <177633461154.3479617.12415344802014608884.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Reject registration of a registered fprobe which is on the fprobe hash table before initializing fprobe. The add_fprobe_hash() checks this re-register fprobe, but since fprobe_init() clears hlist_array field, it is too late to check it. It has to check the re-registration before touncing fprobe. Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- Changes in v6: - Newly added. --- kernel/trace/fprobe.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index dcadf1d23b8a..fc7018b28fdd 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -4,6 +4,7 @@ */ #define pr_fmt(fmt) "fprobe: " fmt =20 +#include #include #include #include @@ -107,7 +108,7 @@ static bool delete_fprobe_node(struct fprobe_hlist_node= *node) } =20 /* Check existence of the fprobe */ -static bool is_fprobe_still_exist(struct fprobe *fp) +static bool fprobe_registered(struct fprobe *fp) { struct hlist_head *head; struct fprobe_hlist *fph; @@ -120,7 +121,7 @@ static bool is_fprobe_still_exist(struct fprobe *fp) } return false; } -NOKPROBE_SYMBOL(is_fprobe_still_exist); +NOKPROBE_SYMBOL(fprobe_registered); =20 static int add_fprobe_hash(struct fprobe *fp) { @@ -132,9 +133,6 @@ static int add_fprobe_hash(struct fprobe *fp) if (WARN_ON_ONCE(!fph)) return -EINVAL; =20 - if (is_fprobe_still_exist(fp)) - return -EEXIST; - head =3D &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)]; hlist_add_head_rcu(&fp->hlist_array->hlist, head); return 0; @@ -149,7 +147,7 @@ static int del_fprobe_hash(struct fprobe *fp) if (WARN_ON_ONCE(!fph)) return -EINVAL; =20 - if (!is_fprobe_still_exist(fp)) + if (!fprobe_registered(fp)) return -ENOENT; =20 fph->fp =3D NULL; @@ -482,7 +480,7 @@ static void fprobe_return(struct ftrace_graph_ret *trac= e, if (!fp) break; curr +=3D FPROBE_HEADER_SIZE_IN_LONG; - if (is_fprobe_still_exist(fp) && !fprobe_disabled(fp)) { + if (fprobe_registered(fp) && !fprobe_disabled(fp)) { if (WARN_ON_ONCE(curr + size > size_words)) break; fp->exit_handler(fp, trace->func, ret_ip, fregs, @@ -841,12 +839,14 @@ int register_fprobe_ips(struct fprobe *fp, unsigned l= ong *addrs, int num) struct fprobe_hlist *hlist_array; int ret, i; =20 + guard(mutex)(&fprobe_mutex); + if (fprobe_registered(fp)) + return -EEXIST; + ret =3D fprobe_init(fp, addrs, num); if (ret) return ret; =20 - mutex_lock(&fprobe_mutex); - hlist_array =3D fp->hlist_array; if (fprobe_is_ftrace(fp)) ret =3D fprobe_ftrace_add_ips(addrs, num); @@ -866,7 +866,6 @@ int register_fprobe_ips(struct fprobe *fp, unsigned lon= g *addrs, int num) delete_fprobe_node(&hlist_array->array[i]); } } - mutex_unlock(&fprobe_mutex); =20 if (ret) fprobe_fail_cleanup(fp); @@ -928,7 +927,7 @@ int unregister_fprobe(struct fprobe *fp) int ret =3D 0, i, count; =20 mutex_lock(&fprobe_mutex); - if (!fp || !is_fprobe_still_exist(fp)) { + if (!fp || !fprobe_registered(fp)) { ret =3D -EINVAL; goto out; } From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75FDE25A2DD; Thu, 16 Apr 2026 10:17:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; 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Thu, 16 Apr 2026 10:17:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334622; bh=gN1BRrqXMRbChB0x61xF2kukdXPqZcRjnyQOsPmr+Ig=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q/P1Rj7Xhn+MeFvOqiaea+KFyNLiW5Jtk1ZP6NYXn4xf+ym8ElOH5+PSbRx7SQ2z2 Bs0hNN5hx7KobjWMU55gxNqBupWDeZCevhVnqTi6zHEjrI0TsaXsB0KRi1o7Us9dY8 mn4Me+pQgA2Zah2uFPy/dXd0wN6yqsZxdaSjYNP8vns7Ev//7cFrJdLO6fQ+UMRJeF q0wUVO/x0/Oq63r9X7lQ5FwkzGpNoVCRRb+P5q3Jf/TtSpwSB08iZcI6T4UxKd9ygG 7aRTsv8tmjz5dejw4Dnhh4UNSk/vrcOGzfcSrxh7+xpzRbJatl6pycbdGd+9r3smC/ swkxhxAUh6ppg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 2/8] tracing/fprobe: Unregister fprobe even if memory allocation fails Date: Thu, 16 Apr 2026 19:16:59 +0900 Message-ID: <177633461941.3479617.12152733686320498504.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) unregister_fprobe() can fail under memory pressure because of memory allocation failure, but this maybe called from module unloading, and usually there is no way to retry it. Moreover. trace_fprobe does not check the return value. To fix this problem, unregister fprobe and fprobe_hash_node even if working memory allocation fails. Anyway, if the last fprobe is removed, the filter will be freed. Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- Changes in v7: - Newly added. --- kernel/trace/fprobe.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index fc7018b28fdd..d634eb8e8b9e 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -934,15 +934,19 @@ int unregister_fprobe(struct fprobe *fp) =20 hlist_array =3D fp->hlist_array; addrs =3D kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL); - if (!addrs) { - ret =3D -ENOMEM; /* TODO: Fallback to one-by-one loop */ - goto out; - } + /* + * This will remove fprobe_hash_node from the hash table even if + * memory allocation fails. However, ftrace_ops will not be updated. + * Anyway, when the last fprobe is unregistered, ftrace_ops is also + * unregistered. + */ + if (!addrs) + pr_warn("Failed to allocate working array. ftrace_ops may not sync.\n"); =20 /* Remove non-synonim ips from table and hash */ count =3D 0; for (i =3D 0; i < hlist_array->size; i++) { - if (!delete_fprobe_node(&hlist_array->array[i])) + if (!delete_fprobe_node(&hlist_array->array[i]) && addrs) addrs[count++] =3D hlist_array->array[i].addr; } del_fprobe_hash(fp); From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1FACF38A720; Thu, 16 Apr 2026 10:17:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334630; cv=none; b=hdhqjkLc0Pz899Zczz5u0Pz5isYz+jWsIc6TfHl4Qu+8S2RA8pPNDkXCVA7HIzE6erWC6BuLfhLzdiWQDIMpFFQQNYY68nwR3eKSnF8QXpV1dqsnXr5O2Ux71E9OxMsV3fuexSb82lWvs0K3Mx7uEsizrLI3qEF+k4cGfwJ+Rh8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334630; c=relaxed/simple; bh=woqz7sbdir7KOqdAyR9p4npc1Sx+eqZR7CNGpdELQUg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XMVOxQ1Q1T/VtdNKajaNEWECSbog6SfThFQia7fPo4qr9BDLRx2+rqL2bE7r1HOmO0zqldS4+3/isdke2vle2VZpZ+SpQGkuUtYXF1FJzQesgGnWpB5eIIRNskawInMCJ9XDqkfw5Kyz779YLxrjVVwhKEhVeUD5fk1xSMHGvzE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Zbw7oaZq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Zbw7oaZq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FF85C2BCAF; Thu, 16 Apr 2026 10:17:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334630; bh=woqz7sbdir7KOqdAyR9p4npc1Sx+eqZR7CNGpdELQUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zbw7oaZqtmnIRY73zXHmBfjrjWiF3bxCxgHccEWi2N1qzfJhGrB2oqwvY8rvCo7Iz GvizNiJBvPGGB9R7NMLTsJa7JXd5FtNyjO9XiU8OZTyhKdDsGGF27EPdqFA2vSUVLP yqpIl2S/d5O7libkox0rtBhb32sp3Dw9NkEIaQlnxZP9Nhe89A1m1DmimeIhl5mVdw ZZtwUgUYmW5Yfs4MdSSjYXj5N2WPA+jDHSmYXjdXi2cU2hwXDPHnwOqm/+tnok3i0G VYV2VOE2Y+q9sI2AEnPYog3e6061L0beqFn4+fdnQZ0ZA2i2uubi/3gpoHDXGebNIj 4ezvLjd9zKUVw== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 3/8] tracing/fprobe: Remove fprobe from hash in failure path Date: Thu, 16 Apr 2026 19:17:07 +0900 Message-ID: <177633462736.3479617.10589205504779632871.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) When register_fprobe_ips() fails, it tries to remove a list of fprobe_hash_node from fprobe_ip_table, but it missed to remove fprobe itself from fprobe_table. Moreover, when removing the fprobe_hash_node which is added to rhltable once, it must use kfree_rcu() after removing from rhltable. To fix these issues, this reuses unregister_fprobe() internal code to rollback the half-way registered fprobe. Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- Changes in v8: - Fix to check return value of add_fprobe_hash() and break loop if insert_fprobe_node() is failed. Changes in v7: - Remove RCU grace period wait, since fprobe itself is not that is not needed. Changes in v6: - Wait for an RCU grace period before returning error in unregister_fprobe_nolock(). Changes in v5: - When rolling back an fprobe that failed to register, the fprobe_hash_node are forcibly removed and warn if failure. Changes in v4: - Remove short-cut case because we always need to upadte ftrace_ops. - Use guard(mutex) in register_fprobe_ips() to unlock it correctly. - Remove redundant !ret check in register_fprobe_ips(). - Do not set hlist_array->size in failure case, instead, hlist_array->array[i].fp is set only when insertion is succeeded. Changes in v3: - Newly added. --- kernel/trace/fprobe.c | 85 +++++++++++++++++++++++++--------------------= ---- 1 file changed, 43 insertions(+), 42 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index d634eb8e8b9e..98c5786bf172 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -79,20 +79,27 @@ static const struct rhashtable_params fprobe_rht_params= =3D { }; =20 /* Node insertion and deletion requires the fprobe_mutex */ -static int insert_fprobe_node(struct fprobe_hlist_node *node) +static int insert_fprobe_node(struct fprobe_hlist_node *node, struct fprob= e *fp) { + int ret; + lockdep_assert_held(&fprobe_mutex); =20 - return rhltable_insert(&fprobe_ip_table, &node->hlist, fprobe_rht_params); + ret =3D rhltable_insert(&fprobe_ip_table, &node->hlist, fprobe_rht_params= ); + /* Set the fprobe pointer if insertion was successful. */ + if (!ret) + WRITE_ONCE(node->fp, fp); + return ret; } =20 /* Return true if there are synonims */ static bool delete_fprobe_node(struct fprobe_hlist_node *node) { - lockdep_assert_held(&fprobe_mutex); bool ret; =20 - /* Avoid double deleting */ + lockdep_assert_held(&fprobe_mutex); + + /* Avoid double deleting and non-inserted nodes */ if (READ_ONCE(node->fp) !=3D NULL) { WRITE_ONCE(node->fp, NULL); rhltable_remove(&fprobe_ip_table, &node->hlist, @@ -757,7 +764,6 @@ static int fprobe_init(struct fprobe *fp, unsigned long= *addrs, int num) fp->hlist_array =3D hlist_array; hlist_array->fp =3D fp; for (i =3D 0; i < num; i++) { - hlist_array->array[i].fp =3D fp; addr =3D ftrace_location(addrs[i]); if (!addr) { fprobe_fail_cleanup(fp); @@ -821,6 +827,8 @@ int register_fprobe(struct fprobe *fp, const char *filt= er, const char *notfilter } EXPORT_SYMBOL_GPL(register_fprobe); =20 +static int unregister_fprobe_nolock(struct fprobe *fp); + /** * register_fprobe_ips() - Register fprobe to ftrace by address. * @fp: A fprobe data structure to be registered. @@ -847,28 +855,22 @@ int register_fprobe_ips(struct fprobe *fp, unsigned l= ong *addrs, int num) if (ret) return ret; =20 - hlist_array =3D fp->hlist_array; if (fprobe_is_ftrace(fp)) ret =3D fprobe_ftrace_add_ips(addrs, num); else ret =3D fprobe_graph_add_ips(addrs, num); - - if (!ret) { - add_fprobe_hash(fp); - for (i =3D 0; i < hlist_array->size; i++) { - ret =3D insert_fprobe_node(&hlist_array->array[i]); - if (ret) - break; - } - /* fallback on insert error */ - if (ret) { - for (i--; i >=3D 0; i--) - delete_fprobe_node(&hlist_array->array[i]); - } + if (ret) { + fprobe_fail_cleanup(fp); + return ret; } =20 + hlist_array =3D fp->hlist_array; + ret =3D add_fprobe_hash(fp); + for (i =3D 0; i < hlist_array->size && !ret; i++) + ret =3D insert_fprobe_node(&hlist_array->array[i], fp); + if (ret) - fprobe_fail_cleanup(fp); + unregister_fprobe_nolock(fp); =20 return ret; } @@ -912,27 +914,12 @@ bool fprobe_is_registered(struct fprobe *fp) return true; } =20 -/** - * unregister_fprobe() - Unregister fprobe. - * @fp: A fprobe data structure to be unregistered. - * - * Unregister fprobe (and remove ftrace hooks from the function entries). - * - * Return 0 if @fp is unregistered successfully, -errno if not. - */ -int unregister_fprobe(struct fprobe *fp) +static int unregister_fprobe_nolock(struct fprobe *fp) { - struct fprobe_hlist *hlist_array; + struct fprobe_hlist *hlist_array =3D fp->hlist_array; unsigned long *addrs =3D NULL; - int ret =3D 0, i, count; + int i, count; =20 - mutex_lock(&fprobe_mutex); - if (!fp || !fprobe_registered(fp)) { - ret =3D -EINVAL; - goto out; - } - - hlist_array =3D fp->hlist_array; addrs =3D kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL); /* * This will remove fprobe_hash_node from the hash table even if @@ -958,12 +945,26 @@ int unregister_fprobe(struct fprobe *fp) =20 kfree_rcu(hlist_array, rcu); fp->hlist_array =3D NULL; + kfree(addrs); =20 -out: - mutex_unlock(&fprobe_mutex); + return 0; +} =20 - kfree(addrs); - return ret; +/** + * unregister_fprobe() - Unregister fprobe. + * @fp: A fprobe data structure to be unregistered. + * + * Unregister fprobe (and remove ftrace hooks from the function entries). + * + * Return 0 if @fp is unregistered successfully, -errno if not. + */ +int unregister_fprobe(struct fprobe *fp) +{ + guard(mutex)(&fprobe_mutex); + if (!fp || !fprobe_registered(fp)) + return -EINVAL; + + return unregister_fprobe_nolock(fp); } EXPORT_SYMBOL_GPL(unregister_fprobe); From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3743825A2DD; Thu, 16 Apr 2026 10:17:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334638; cv=none; b=SiFsxyD3ezfqy/HIXu06FcC++7ULZbs08hlLOrxBa7z9SHtMNHC0wCD08kVL09iQfMDckXVEpf7tYXTwDSH01BOrKkz+T38bV1HK8VFLC1Q88Xbo7+OeujYLlC10qcxm9xH/HjaXyLV4/aK3LURmId8NrsvKuMtYNe6Y4E+dDqk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334638; c=relaxed/simple; bh=+g9AWORtn5BZSThMiqS8wwoMu0hQ7oESVufvcz59dnw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) fprobe_remove_node_in_module() is called under RCU read locked, but this invokes kcalloc() if there are more than 8 fprobes installed on the module. Sashiko warns it because kcalloc() can sleep [1]. [1] https://sashiko.dev/#/patchset/177552432201.853249.5125045538812833325= .stgit%40mhiramat.tok.corp.google.com To fix this issue, expand the batch size to 128 and do not expand the fprobe_addr_list, but just cancel walking on fprobe_ip_table, update fgraph/ftrace_ops and retry the loop again. Fixes: 0de4c70d04a4 ("tracing: fprobe: use rhltable for fprobe_ip_table") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- Changes in v6: - Retry outside rhltable_walk_enter/exit() again. Changes in v5: - Skip updating ftrace_ops when fails to allocate memory in module unloading. Changes in v4: - fix a build error typo in case of CONFIG_DYNAMIC_FTRACE=3Dn. Changes in v3: - Retry inside rhltable_walk_enter/exit(). - Rename fprobe_set_ips() to fprobe_remove_ips(). - Rename 'retry' label to 'again'. --- kernel/trace/fprobe.c | 92 ++++++++++++++++++++++++---------------------= ---- 1 file changed, 45 insertions(+), 47 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 98c5786bf172..77d4449f20f7 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -343,11 +343,10 @@ static bool fprobe_is_ftrace(struct fprobe *fp) } =20 #ifdef CONFIG_MODULES -static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remov= e, - int reset) +static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); - ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, remove, reset); + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); + ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, 1, 0); } #endif #else @@ -366,10 +365,9 @@ static bool fprobe_is_ftrace(struct fprobe *fp) } =20 #ifdef CONFIG_MODULES -static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remov= e, - int reset) +static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); } #endif #endif /* !CONFIG_DYNAMIC_FTRACE_WITH_ARGS && !CONFIG_DYNAMIC_FTRACE_WITH_= REGS */ @@ -543,7 +541,7 @@ static void fprobe_graph_remove_ips(unsigned long *addr= s, int num) =20 #ifdef CONFIG_MODULES =20 -#define FPROBE_IPS_BATCH_INIT 8 +#define FPROBE_IPS_BATCH_INIT 128 /* instruction pointer address list */ struct fprobe_addr_list { int index; @@ -551,45 +549,24 @@ struct fprobe_addr_list { unsigned long *addrs; }; =20 -static int fprobe_addr_list_add(struct fprobe_addr_list *alist, unsigned l= ong addr) +static int fprobe_remove_node_in_module(struct module *mod, struct fprobe_= hlist_node *node, + struct fprobe_addr_list *alist) { - unsigned long *addrs; - - /* Previously we failed to expand the list. */ - if (alist->index =3D=3D alist->size) - return -ENOSPC; - - alist->addrs[alist->index++] =3D addr; - if (alist->index < alist->size) + if (!within_module(node->addr, mod)) return 0; =20 - /* Expand the address list */ - addrs =3D kcalloc(alist->size * 2, sizeof(*addrs), GFP_KERNEL); - if (!addrs) - return -ENOMEM; - - memcpy(addrs, alist->addrs, alist->size * sizeof(*addrs)); - alist->size *=3D 2; - kfree(alist->addrs); - alist->addrs =3D addrs; + if (delete_fprobe_node(node)) + return 0; + /* If no address list is available, we can't track this address. */ + if (!alist->addrs) + return 0; =20 + alist->addrs[alist->index++] =3D node->addr; + if (alist->index =3D=3D alist->size) + return -ENOSPC; return 0; } =20 -static void fprobe_remove_node_in_module(struct module *mod, struct fprobe= _hlist_node *node, - struct fprobe_addr_list *alist) -{ - if (!within_module(node->addr, mod)) - return; - if (delete_fprobe_node(node)) - return; - /* - * If failed to update alist, just continue to update hlist. - * Therefore, at list user handler will not hit anymore. - */ - fprobe_addr_list_add(alist, node->addr); -} - /* Handle module unloading to manage fprobe_ip_table. */ static int fprobe_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -598,29 +575,50 @@ static int fprobe_module_callback(struct notifier_blo= ck *nb, struct fprobe_hlist_node *node; struct rhashtable_iter iter; struct module *mod =3D data; + bool retry; =20 if (val !=3D MODULE_STATE_GOING) return NOTIFY_DONE; =20 alist.addrs =3D kcalloc(alist.size, sizeof(*alist.addrs), GFP_KERNEL); - /* If failed to alloc memory, we can not remove ips from hash. */ - if (!alist.addrs) - return NOTIFY_DONE; + /* + * If failed to alloc memory, ftrace_ops will not be able to remove ips f= rom + * hash, but we can still remove nodes from fprobe_ip_table, so we can av= oid + * the potential wrong callback. So just print a warning here and try to + * continue without address list. + */ + WARN_ONCE(!alist.addrs, + "Failed to allocate memory for fprobe_addr_list, ftrace_ops will not be = updated"); =20 mutex_lock(&fprobe_mutex); +again: + retry =3D false; + alist.index =3D 0; rhltable_walk_enter(&fprobe_ip_table, &iter); do { rhashtable_walk_start(&iter); =20 while ((node =3D rhashtable_walk_next(&iter)) && !IS_ERR(node)) - fprobe_remove_node_in_module(mod, node, &alist); + if (fprobe_remove_node_in_module(mod, node, &alist) < 0) { + retry =3D true; + break; + } =20 rhashtable_walk_stop(&iter); - } while (node =3D=3D ERR_PTR(-EAGAIN)); + } while (node =3D=3D ERR_PTR(-EAGAIN) && !retry); rhashtable_walk_exit(&iter); + /* Remove any ips from hash table(s) */ + if (alist.index > 0) { + fprobe_remove_ips(alist.addrs, alist.index); + /* + * If we break rhashtable walk loop except for -EAGAIN, we need + * to restart looping from start for safety. Anyway, this is + * not a hotpath. + */ + if (retry) + goto again; + } =20 - if (alist.index > 0) - fprobe_set_ips(alist.addrs, alist.index, 1, 0); mutex_unlock(&fprobe_mutex); =20 kfree(alist.addrs); From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A58538A720; Thu, 16 Apr 2026 10:17:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334646; cv=none; b=DzVQXafdjUXH4S09hxEizDJnJO5Q+tWVVtncXZXygkS+qAXBP2kAoIc8UvZZYM4CJwxjNhHtBs6osmMDNOmxol4HLGwIAMVYz+RrXSGY5J7ti+c/IYjlEpJqI/2EIdQ4fNvlKlTgw+hWktl70xrxnuWyFqmnvk+k2xcaSreIQ6E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334646; c=relaxed/simple; bh=77reKZxTgRKMRrJY5y2d930vw4VpPYZdtgY4qQo5ZPA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=OhiE7mPHJBsDYIEYyTmFM16G2eY8LHAHUnVwZRb82lFd0xHz8YIq6G8k7KsMDs9XPYBRNYFD6IBHsvawuNrGFOpwV+Egq6mKC0wMwNT49YHuCF3XnOp+IRVOLzvd1+vpjAZVVg9nteXT5YLWvqYJMIH9/BsH3C6wkt1pFdGbjWA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iEQZFCcm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iEQZFCcm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E748AC2BCAF; Thu, 16 Apr 2026 10:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334645; bh=77reKZxTgRKMRrJY5y2d930vw4VpPYZdtgY4qQo5ZPA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iEQZFCcmmhtncO2XK2ThVqMluow6hGD+5RyLNrxqZqr7lf+X1pDzZkzgw7qnDFznt E46ZRnNXEd0BBLK1f7Ms+9C/adKgIfIJB1W0HYKeyZy3iZALJBCVoIgx6rJfrxHo4I WlCmKx6HfaeBAcC+6y08QUlAkfcfsMi+3r2VqMQljyjpSRfJCJK/ah4p4QhJ0q/YPB x0NlIj1lLimNbn/VFvzlyMEYGzyhywSPdHa7ZwxsE7Du3nyx3Uil1hV00kVMXTTQi1 ak0rONxFs4rm7Q9ES0Tqgr+RBLeTgU3wmvQ7MASpqNATTTxykEka+/PUUH7VVrZuIh VDu51Lh+kOIdg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 5/8] tracing/fprobe: Check the same type fprobe on table as the unregistered one Date: Thu, 16 Apr 2026 19:17:23 +0900 Message-ID: <177633464318.3479617.2388046188136239875.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Commit 2c67dc457bc6 ("tracing: fprobe: optimization for entry only case") introduced a different ftrace_ops for entry-only fprobes. However, when unregistering an fprobe, the kernel only checks if another fprobe exists at the same address, without checking which type of fprobe it is. If different fprobes are registered at the same address, the same address will be registered in both fgraph_ops and ftrace_ops, but only one of them will be deleted when unregistering. (the one removed first will not be deleted from the ops). This results in junk entries remaining in either fgraph_ops or ftrace_ops. For example: =3D=3D=3D=3D=3D=3D=3D cd /sys/kernel/tracing # 'Add entry and exit events on the same place' echo 'f:event1 vfs_read' >> dynamic_events echo 'f:event2 vfs_read%return' >> dynamic_events # 'Enable both of them' echo 1 > events/fprobes/enable cat enabled_functions vfs_read (2) ->arch_ftrace_ops_list_func+0x0/0x210 # 'Disable and remove exit event' echo 0 > events/fprobes/event2/enable echo -:event2 >> dynamic_events # 'Disable and remove all events' echo 0 > events/fprobes/enable echo > dynamic_events # 'Add another event' echo 'f:event3 vfs_open%return' > dynamic_events cat dynamic_events f:fprobes/event3 vfs_open%return echo 1 > events/fprobes/enable cat enabled_functions vfs_open (1) tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x= 60) ->ftrace_graph_func+0x0/0x60 subops: {ent:fprobe_fgraph_entry+0x0/0x= 620 ret:fprobe_return+0x0/0x150} vfs_read (1) tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x= 60) ->ftrace_graph_func+0x0/0x60 subops: {ent:fprobe_fgraph_entry+0x0/0x= 620 ret:fprobe_return+0x0/0x150} =3D=3D=3D=3D=3D=3D=3D As you can see, an entry for the vfs_read remains. To fix this issue, when unregistering, the kernel should also check if there is the same type of fprobes still exist at the same address, and if not, delete its entry from either fgraph_ops or ftrace_ops. Fixes: 2c67dc457bc6 ("tracing: fprobe: optimization for entry only case") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/fprobe.c | 82 +++++++++++++++++++++++++++++++++++++++------= ---- 1 file changed, 65 insertions(+), 17 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 77d4449f20f7..f2c30587ab26 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -92,11 +92,8 @@ static int insert_fprobe_node(struct fprobe_hlist_node *= node, struct fprobe *fp) return ret; } =20 -/* Return true if there are synonims */ -static bool delete_fprobe_node(struct fprobe_hlist_node *node) +static void delete_fprobe_node(struct fprobe_hlist_node *node) { - bool ret; - lockdep_assert_held(&fprobe_mutex); =20 /* Avoid double deleting and non-inserted nodes */ @@ -105,13 +102,6 @@ static bool delete_fprobe_node(struct fprobe_hlist_nod= e *node) rhltable_remove(&fprobe_ip_table, &node->hlist, fprobe_rht_params); } - - rcu_read_lock(); - ret =3D !!rhltable_lookup(&fprobe_ip_table, &node->addr, - fprobe_rht_params); - rcu_read_unlock(); - - return ret; } =20 /* Check existence of the fprobe */ @@ -342,6 +332,32 @@ static bool fprobe_is_ftrace(struct fprobe *fp) return !fp->exit_handler; } =20 +static bool fprobe_exists_on_hash(unsigned long ip, bool ftrace) +{ + struct rhlist_head *head, *pos; + struct fprobe_hlist_node *node; + struct fprobe *fp; + + guard(rcu)(); + head =3D rhltable_lookup(&fprobe_ip_table, &ip, + fprobe_rht_params); + if (!head) + return false; + /* We have to check the same type on the list. */ + rhl_for_each_entry_rcu(node, pos, head, hlist) { + if (node->addr !=3D ip) + break; + fp =3D READ_ONCE(node->fp); + if (likely(fp)) { + if ((!ftrace && fp->exit_handler) || + (ftrace && !fp->exit_handler)) + return true; + } + } + + return false; +} + #ifdef CONFIG_MODULES static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { @@ -364,6 +380,29 @@ static bool fprobe_is_ftrace(struct fprobe *fp) return false; } =20 +static bool fprobe_exists_on_hash(unsigned long ip, bool ftrace __maybe_un= used) +{ + struct rhlist_head *head, *pos; + struct fprobe_hlist_node *node; + struct fprobe *fp; + + guard(rcu)(); + head =3D rhltable_lookup(&fprobe_ip_table, &ip, + fprobe_rht_params); + if (!head) + return false; + /* We only need to check fp is there. */ + rhl_for_each_entry_rcu(node, pos, head, hlist) { + if (node->addr !=3D ip) + break; + fp =3D READ_ONCE(node->fp); + if (likely(fp)) + return true; + } + + return false; +} + #ifdef CONFIG_MODULES static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { @@ -552,18 +591,25 @@ struct fprobe_addr_list { static int fprobe_remove_node_in_module(struct module *mod, struct fprobe_= hlist_node *node, struct fprobe_addr_list *alist) { + lockdep_assert_in_rcu_read_lock(); + if (!within_module(node->addr, mod)) return 0; =20 - if (delete_fprobe_node(node)) - return 0; + delete_fprobe_node(node); /* If no address list is available, we can't track this address. */ if (!alist->addrs) return 0; + /* + * Don't care the type here, because all fprobes on the same + * address must be removed eventually. + */ + if (!rhltable_lookup(&fprobe_ip_table, &node->addr, fprobe_rht_params)) { + alist->addrs[alist->index++] =3D node->addr; + if (alist->index =3D=3D alist->size) + return -ENOSPC; + } =20 - alist->addrs[alist->index++] =3D node->addr; - if (alist->index =3D=3D alist->size) - return -ENOSPC; return 0; } =20 @@ -931,7 +977,9 @@ static int unregister_fprobe_nolock(struct fprobe *fp) /* Remove non-synonim ips from table and hash */ count =3D 0; for (i =3D 0; i < hlist_array->size; i++) { - if (!delete_fprobe_node(&hlist_array->array[i]) && addrs) + delete_fprobe_node(&hlist_array->array[i]); + if (addrs && !fprobe_exists_on_hash(hlist_array->array[i].addr, + fprobe_is_ftrace(fp))) addrs[count++] =3D hlist_array->array[i].addr; } del_fprobe_hash(fp); From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D848B39DBEE; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GsFvF+KE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE471C2BCB0; Thu, 16 Apr 2026 10:17:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334653; bh=Nfd3todE/ayttr2tkh3sPD9Tjk3a7gqq3ycu4KO/QsE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GsFvF+KEK2nDrnn7YluJDHVQGe2gM9HDCUKxrHRaNfzEUKQ5T2sgwIRZZffsHZI1q U1IvUoNVw/1QqBz4hTDcPSRpsajISBR1hyEvx+CSPgOZXXuNXrog8Nqb/2BekdAjBu kGL+Dj8eX2lawPsskWR7emEZuYAxozhdak7np5rnY9FwJg4ELOKS0VV37OyEr3TaRn WUIi737SjpZ1ob7BUwYu7eBvv4FRl5N9R5VvN4zlL8VJHdCmes+CxaOQW6ouVw8PRQ n+j4KOJmw22C7Mp/oazkxHQMCvAiBZeaYueBdbn6QuQxIoFo9Ga7whxApVzbyHmtdJ v6zbfygOBk1aA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 6/8] tracing/fprobe: Fix to unregister ftrace_ops if it is empty on module unloading Date: Thu, 16 Apr 2026 19:17:31 +0900 Message-ID: <177633465115.3479617.5433794585008902596.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Fix fprobe to unregister ftrace_ops if corresponding type of fprobe does not exist on the fprobe_ip_table and it is expected to be empty when unloading modules. Since ftrace thinks that the empty hash means everything to be traced, if we set fprobes only on the unloaded module, all functions are traced unexpectedly after unloading module. e.g. # modprobe xt_LOG.ko # echo 'f:test log_tg*' > dynamic_events # echo 1 > events/fprobes/test/enable # cat enabled_functions log_tg [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_ftrace_en= try+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490 log_tg_check [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_f= trace_entry+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490 log_tg_destroy [xt_LOG] (1) tramp: 0xffffffffa0004000 (fprobe_f= trace_entry+0x0/0x490) ->fprobe_ftrace_entry+0x0/0x490 # rmmod xt_LOG # wc -l enabled_functions 34085 enabled_functions Signed-off-by: Masami Hiramatsu (Google) --- Changes in v8: - Fix to check fprobe_graph/ftrace_registered flag directly when registering ftrace_ops. Changes in v7: - Fix to split checking whether ftrace_ops is registered from the number of registered fprobes, because ftrace_ops can be unregistered in module unloading. Changes in v6: - Newly added. --- kernel/trace/fprobe.c | 211 +++++++++++++++++++++++++++++++++++++--------= ---- 1 file changed, 161 insertions(+), 50 deletions(-) diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index f2c30587ab26..3c390b90a99f 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -79,7 +79,7 @@ static const struct rhashtable_params fprobe_rht_params = =3D { }; =20 /* Node insertion and deletion requires the fprobe_mutex */ -static int insert_fprobe_node(struct fprobe_hlist_node *node, struct fprob= e *fp) +static int __insert_fprobe_node(struct fprobe_hlist_node *node, struct fpr= obe *fp) { int ret; =20 @@ -92,7 +92,7 @@ static int insert_fprobe_node(struct fprobe_hlist_node *n= ode, struct fprobe *fp) return ret; } =20 -static void delete_fprobe_node(struct fprobe_hlist_node *node) +static void __delete_fprobe_node(struct fprobe_hlist_node *node) { lockdep_assert_held(&fprobe_mutex); =20 @@ -250,7 +250,72 @@ static inline int __fprobe_kprobe_handler(unsigned lon= g ip, unsigned long parent return ret; } =20 +static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgra= ph_ops *gops, + struct ftrace_regs *fregs); +static void fprobe_return(struct ftrace_graph_ret *trace, + struct fgraph_ops *gops, + struct ftrace_regs *fregs); + +static struct fgraph_ops fprobe_graph_ops =3D { + .entryfunc =3D fprobe_fgraph_entry, + .retfunc =3D fprobe_return, +}; +/* Number of fgraph fprobes */ +static int fprobe_graph_active; +/* Number of fgraph fprobe nodes */ +static int nr_fgraph_fprobes; +/* Is fprobe_graph_ops registered? */ +static bool fprobe_graph_registered; + +/* Add @addrs to the ftrace filter and register fgraph if needed. */ +static int fprobe_graph_add_ips(unsigned long *addrs, int num) +{ + int ret; + + lockdep_assert_held(&fprobe_mutex); + + ret =3D ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0); + if (ret) + return ret; + + if (!fprobe_graph_registered) { + ret =3D register_ftrace_graph(&fprobe_graph_ops); + if (WARN_ON_ONCE(ret)) { + ftrace_free_filter(&fprobe_graph_ops.ops); + return ret; + } + fprobe_graph_registered =3D true; + } + fprobe_graph_active++; + return 0; +} + +static void __fprobe_graph_unregister(void) +{ + if (fprobe_graph_registered) { + unregister_ftrace_graph(&fprobe_graph_ops); + ftrace_free_filter(&fprobe_graph_ops.ops); + fprobe_graph_registered =3D false; + } +} + +/* Remove @addrs from the ftrace filter and unregister fgraph if possible.= */ +static void fprobe_graph_remove_ips(unsigned long *addrs, int num) +{ + lockdep_assert_held(&fprobe_mutex); + + if (!fprobe_graph_active) + return; + + fprobe_graph_active--; + if (!fprobe_graph_active) + __fprobe_graph_unregister(); + else if (num) + ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0); +} + #if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) || defined(CONFIG_DYNAMIC_FTR= ACE_WITH_REGS) + /* ftrace_ops callback, this processes fprobes which have only entry_handl= er. */ static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct ftrace_regs *fregs) @@ -293,7 +358,12 @@ static struct ftrace_ops fprobe_ftrace_ops =3D { .func =3D fprobe_ftrace_entry, .flags =3D FTRACE_OPS_FL_SAVE_ARGS, }; +/* Number of fgraph fprobes */ static int fprobe_ftrace_active; +/* Number of ftrace fprobe nodes */ +static int nr_ftrace_fprobes; +/* Is fprobe_ftrace_ops registered? */ +static bool fprobe_ftrace_registered; =20 static int fprobe_ftrace_add_ips(unsigned long *addrs, int num) { @@ -305,25 +375,38 @@ static int fprobe_ftrace_add_ips(unsigned long *addrs= , int num) if (ret) return ret; =20 - if (!fprobe_ftrace_active) { + if (!fprobe_ftrace_registered) { ret =3D register_ftrace_function(&fprobe_ftrace_ops); if (ret) { ftrace_free_filter(&fprobe_ftrace_ops); return ret; } + fprobe_ftrace_registered =3D true; } fprobe_ftrace_active++; return 0; } =20 +static void __fprobe_ftrace_unregister(void) +{ + if (fprobe_ftrace_registered) { + unregister_ftrace_function(&fprobe_ftrace_ops); + ftrace_free_filter(&fprobe_ftrace_ops); + fprobe_ftrace_registered =3D false; + } +} + static void fprobe_ftrace_remove_ips(unsigned long *addrs, int num) { lockdep_assert_held(&fprobe_mutex); =20 + if (!fprobe_ftrace_active) + return; + fprobe_ftrace_active--; if (!fprobe_ftrace_active) - unregister_ftrace_function(&fprobe_ftrace_ops); - if (num) + __fprobe_ftrace_unregister(); + else if (num) ftrace_set_filter_ips(&fprobe_ftrace_ops, addrs, num, 1, 0); } =20 @@ -332,6 +415,40 @@ static bool fprobe_is_ftrace(struct fprobe *fp) return !fp->exit_handler; } =20 +/* Node insertion and deletion requires the fprobe_mutex */ +static int insert_fprobe_node(struct fprobe_hlist_node *node, struct fprob= e *fp) +{ + int ret; + + lockdep_assert_held(&fprobe_mutex); + + ret =3D __insert_fprobe_node(node, fp); + if (!ret) { + if (fprobe_is_ftrace(fp)) + nr_ftrace_fprobes++; + else + nr_fgraph_fprobes++; + } + + return ret; +} + +static void delete_fprobe_node(struct fprobe_hlist_node *node) +{ + struct fprobe *fp; + + lockdep_assert_held(&fprobe_mutex); + + fp =3D READ_ONCE(node->fp); + if (fp) { + if (fprobe_is_ftrace(fp)) + nr_ftrace_fprobes--; + else + nr_fgraph_fprobes--; + } + __delete_fprobe_node(node); +} + static bool fprobe_exists_on_hash(unsigned long ip, bool ftrace) { struct rhlist_head *head, *pos; @@ -361,8 +478,15 @@ static bool fprobe_exists_on_hash(unsigned long ip, bo= ol ftrace) #ifdef CONFIG_MODULES static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); - ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, 1, 0); + if (!nr_fgraph_fprobes) + __fprobe_graph_unregister(); + else + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); + + if (!nr_ftrace_fprobes) + __fprobe_ftrace_unregister(); + else + ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, 1, 0); } #endif #else @@ -380,6 +504,32 @@ static bool fprobe_is_ftrace(struct fprobe *fp) return false; } =20 +/* Node insertion and deletion requires the fprobe_mutex */ +static int insert_fprobe_node(struct fprobe_hlist_node *node, struct fprob= e *fp) +{ + int ret; + + lockdep_assert_held(&fprobe_mutex); + + ret =3D __insert_fprobe_node(node, fp); + if (!ret) + nr_fgraph_fprobes++; + + return ret; +} + +static void delete_fprobe_node(struct fprobe_hlist_node *node) +{ + struct fprobe *fp; + + lockdep_assert_held(&fprobe_mutex); + + fp =3D READ_ONCE(node->fp); + if (fp) + nr_fgraph_fprobes--; + __delete_fprobe_node(node); +} + static bool fprobe_exists_on_hash(unsigned long ip, bool ftrace __maybe_un= used) { struct rhlist_head *head, *pos; @@ -406,7 +556,10 @@ static bool fprobe_exists_on_hash(unsigned long ip, bo= ol ftrace __maybe_unused) #ifdef CONFIG_MODULES static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); + if (!nr_fgraph_fprobes) + __fprobe_graph_unregister(); + else + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); } #endif #endif /* !CONFIG_DYNAMIC_FTRACE_WITH_ARGS && !CONFIG_DYNAMIC_FTRACE_WITH_= REGS */ @@ -536,48 +689,6 @@ static void fprobe_return(struct ftrace_graph_ret *tra= ce, } NOKPROBE_SYMBOL(fprobe_return); =20 -static struct fgraph_ops fprobe_graph_ops =3D { - .entryfunc =3D fprobe_fgraph_entry, - .retfunc =3D fprobe_return, -}; -static int fprobe_graph_active; - -/* Add @addrs to the ftrace filter and register fgraph if needed. */ -static int fprobe_graph_add_ips(unsigned long *addrs, int num) -{ - int ret; - - lockdep_assert_held(&fprobe_mutex); - - ret =3D ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0); - if (ret) - return ret; - - if (!fprobe_graph_active) { - ret =3D register_ftrace_graph(&fprobe_graph_ops); - if (WARN_ON_ONCE(ret)) { - ftrace_free_filter(&fprobe_graph_ops.ops); - return ret; - } - } - fprobe_graph_active++; - return 0; -} - -/* Remove @addrs from the ftrace filter and unregister fgraph if possible.= */ -static void fprobe_graph_remove_ips(unsigned long *addrs, int num) -{ - lockdep_assert_held(&fprobe_mutex); - - fprobe_graph_active--; - /* Q: should we unregister it ? */ - if (!fprobe_graph_active) - unregister_ftrace_graph(&fprobe_graph_ops); - - if (num) - ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0); -} - #ifdef CONFIG_MODULES =20 #define FPROBE_IPS_BATCH_INIT 128 From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ECA9D37DEBC; Thu, 16 Apr 2026 10:17:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334662; cv=none; b=N6xiLFR3smAls/3CkJrrHLyY83THicojJLo2+tEPihgpR0lof0KOsgPtmLlr2gr88K+Qh8nZ4EPM8DuU8czYv8D8XKCiGHm1DdVnp9QVLld8TdugJxf6ovmLASzGK3kXPADjQRgZwrDB6AJnihLO9a19nMfIl1g62xG5EFPXVTE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776334662; c=relaxed/simple; bh=Eohmu4mW9zjBee6XRnym8+P1pEMi/WA65MRYY2VIZvo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=h3s4xICOLzrHKBkEGwYHxqxP01bTFJ7LqrMCrsKI7ezaReFN77drmrb6Xg95SlKgeEMXyghn4KQQq4g0jnLdKl1nbyT3w0NfmUjpiVe+7dSg9BU3LaPO4nHVLWWhAOyeQZQNV1F4eidEs8fxm22FBaJvgGL6lnR4tWZndQipteg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fs7uOeJ0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fs7uOeJ0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A348EC2BCAF; Thu, 16 Apr 2026 10:17:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334661; bh=Eohmu4mW9zjBee6XRnym8+P1pEMi/WA65MRYY2VIZvo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fs7uOeJ0qqVQcm0F8AZqrIJ0eck8Go9JyFTXbqmIc7cgFOhTxOo++5ik4/YYp8X2f tBhFdw65bPN/o7oZ3kF90mRVnWAWbrZ9ZuTvxvdt9gOu2bosZTYHM55yCXZaLoPNB/ +4NQMLj9raGi0ALsJafI6fCzE1SA7ih8gWx/VB2QUFX3FLEvLnaa+Ph1HPUTnNYFXu PAsqK+vIzwDAPW2M9qpqbDbwFjCsdKyFury0JnrSMJcCl8rmxhBGmbIokLLmlulAqW nepvLKmGZs7IOsAZIqDwI8yYuWCtfeM4l1wLEfOi0DJ+FjTpnXvi7QacHAsz2K5wIa g6V/iAofljwyQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 7/8] selftests/ftrace: Add a testcase for fprobe events on module Date: Thu, 16 Apr 2026 19:17:39 +0900 Message-ID: <177633465902.3479617.16621806378405730791.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add a testcase for fprobe events on module, which unloads a kernel module on which fprobe events are probing and ensure the ftrace hash map is cleared correctly. Signed-off-by: Masami Hiramatsu (Google) --- .../test.d/dynevent/add_remove_fprobe_module.tc | 61 ++++++++++++++++= ++++ 1 file changed, 61 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remo= ve_fprobe_module.tc diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fpro= be_module.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fp= robe_module.tc new file mode 100644 index 000000000000..500942e9d8d6 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_modu= le.tc @@ -0,0 +1,61 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Generic dynamic event - add/remove fprobe events on module +# requires: dynamic_events "f[:[/][]] [%return] [= ]":README enabled_functions + +rmmod trace-events-sample ||: +if ! modprobe trace-events-sample ; then + echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EV= ENTS=3Dm" + exit_unresolved; +fi +trap "rmmod trace-events-sample" EXIT + +echo 0 > events/enable +echo > dynamic_events + +FUNC1=3D'foo_bar*' +FUNC2=3D'vfs_read' + +:;: "Add an event on the test module" ;: +echo "f:test1 $FUNC1" >> dynamic_events +echo 1 > events/fprobes/test1/enable + +:;: "Ensure it is enabled" ;: +funcs=3D`cat enabled_functions | wc -l` +test $funcs -ne 0 + +:;: "Check the enabled_functions is cleared on unloading" ;: +rmmod trace_events_sample +funcs=3D`cat enabled_functions | wc -l` +test $funcs -eq 0 + +:;: "Check it is kept clean" ;: +modprobe trace-events-sample +echo 1 > events/fprobes/test1/enable || echo "OK" +funcs=3D`cat enabled_functions | wc -l` +test $funcs -eq 0 + +:;: "Add another event not on the test module" ;: +echo "f:test2 $FUNC2" >> dynamic_events +echo 1 > events/fprobes/test2/enable + +:;: "Ensure it is enabled" ;: +ofuncs=3D`cat enabled_functions | wc -l` +test $ofuncs -ne 0 + +:;: "Disable and remove the first event" +echo 0 > events/fprobes/test1/enable +echo "-:fprobes/test1" >> dynamic_events +funcs=3D`cat enabled_functions | wc -l` +test $ofuncs -eq $funcs + +:;: "Disable and remove other events" ;: +echo 0 > events/fprobes/enable +echo > dynamic_events +funcs=3D`cat enabled_functions | wc -l` +test $funcs -eq 0 + + +rmmod trace-events-sample +trap "" EXIT +clear_trace From nobody Tue Jun 16 05:02:45 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 744D354654; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sE5oNrdJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27145C2BCAF; Thu, 16 Apr 2026 10:17:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776334671; bh=tZR2BVMsPTdwmjNRnZOzYXc0zoDf5+38hsPHRSxqelg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sE5oNrdJ/PXxMwtwpYqqE1LgdY7/KtIQxWO8gNyr8g7DxF4KWvldsMXI5hYAM5cXs hTRc1XlSiVMFbmvGg140Kp3J6lM/uhwWywI/mMWAiraFGZBi6Rr6jqyjc0la1W8xAq 7Lg8kg8GnGTJaSsuxlslq/e6/4HrbQZjYNkbzn+HMDn7893FNMbAP6lBHsS7LkILPd pQQdld7oKgeqPFGA92zJ83eLjipx1wxrZpONdF+VP+gmu7s5lmEgCjjlk+P/icpUPm cvtIoPzUBPs18kTWNWk+Wd926dHSXU3BWe0pWJOIkVTEBfsWIEKXHFCwoqJiOJ2LZj zYg58n3z4vSEQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Masami Hiramatsu Cc: Menglong Dong , Mathieu Desnoyers , jiang.biao@linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v8 8/8] selftests/ftrace: Add a testcase for multiple fprobe events Date: Thu, 16 Apr 2026 19:17:47 +0900 Message-ID: <177633466683.3479617.15493325206503059547.stgit@mhiramat.tok.corp.google.com> X-Mailer: git-send-email 2.54.0.rc1.513.gad8abe7a5a-goog In-Reply-To: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> References: <177633460058.3479617.11868368413034643565.stgit@mhiramat.tok.corp.google.com> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add a testcase for multiple fprobe events on the same function so that it clears ftrace hash map correctly when removing the events. Signed-off-by: Masami Hiramatsu (Google) --- .../test.d/dynevent/add_remove_multiple_fprobe.tc | 69 ++++++++++++++++= ++++ 1 file changed, 69 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remo= ve_multiple_fprobe.tc diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_mult= iple_fprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_= multiple_fprobe.tc new file mode 100644 index 000000000000..f2cbf2ffd29b --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_multiple_fp= robe.tc @@ -0,0 +1,69 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Generic dynamic event - add/remove multiple fprobe events o= n the same function +# requires: dynamic_events "f[:[/][]] [%return] [= ]":README enabled_functions + +echo 0 > events/enable +echo > dynamic_events + +PLACE=3Dvfs_read +PLACE2=3Dvfs_open + +:;: 'Ensure no other ftrace user' ;: +test `cat enabled_functions | wc -l` -eq 0 || exit_unresolved + +:;: 'Test case 1: leave entry event' ;: +:;: 'Add entry and exit events on the same place' ;: +echo "f:event1 ${PLACE}" >> dynamic_events +echo "f:event2 ${PLACE}%return" >> dynamic_events + +:;: 'Enable both of them' ;: +echo 1 > events/fprobes/enable +test `cat enabled_functions | wc -l` -eq 1 + +:;: 'Disable and remove exit event' ;: +echo 0 > events/fprobes/event2/enable +echo -:event2 >> dynamic_events + +:;: 'Disable and remove all events' ;: +echo 0 > events/fprobes/enable +echo > dynamic_events + +:;: 'Add another event' ;: +echo "f:event3 ${PLACE2}%return" > dynamic_events +echo 1 > events/fprobes/enable +test `cat enabled_functions | wc -l` -eq 1 + +:;: 'No other ftrace user' ;: +echo 0 > events/fprobes/enable +echo > dynamic_events +test `cat enabled_functions | wc -l` -eq 0 + +:;: 'Test case 2: leave exit event' ;: +:;: 'Add entry and exit events on the same place' ;: +echo "f:event1 ${PLACE}" >> dynamic_events +echo "f:event2 ${PLACE}%return" >> dynamic_events + +:;: 'Enable both of them' ;: +echo 1 > events/fprobes/enable +test `cat enabled_functions | wc -l` -eq 1 + +:;: 'Disable and remove entry event' ;: +echo 0 > events/fprobes/event1/enable +echo -:event1 >> dynamic_events + +:;: 'Disable and remove all events' ;: +echo 0 > events/fprobes/enable +echo > dynamic_events + +:;: 'Add another event' ;: +echo "f:event3 ${PLACE2}" > dynamic_events +echo 1 > events/fprobes/enable +test `cat enabled_functions | wc -l` -eq 1 + +:;: 'No other ftrace user' ;: +echo 0 > events/fprobes/enable +echo > dynamic_events +test `cat enabled_functions | wc -l` -eq 0 + +clear_trace