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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v5 06/23] mm/ksw: add singleton /proc/kstackwatch interface Date: Wed, 24 Sep 2025 19:50:49 +0800 Message-ID: <20250924115124.194940-7-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250924115124.194940-1-wangjinchao600@gmail.com> References: <20250924115124.194940-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Provide the /proc/kstackwatch file to read or update the configuration. Only a single process can open this file at a time, enforced using atomic config_file_busy, to prevent concurrent access. ksw_get_config() exposes the configuration pointer as const. Signed-off-by: Jinchao Wang --- mm/kstackwatch/kernel.c | 77 +++++++++++++++++++++++++++++++++++- mm/kstackwatch/kstackwatch.h | 3 ++ 2 files changed, 79 insertions(+), 1 deletion(-) diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index 3b7009033dd4..4a06ddadd9c7 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -3,11 +3,15 @@ =20 #include #include +#include +#include #include +#include =20 #include "kstackwatch.h" =20 static struct ksw_config *ksw_config; +static atomic_t config_file_busy =3D ATOMIC_INIT(0); =20 struct param_map { const char *name; /* long name */ @@ -74,7 +78,7 @@ static int ksw_parse_param(struct ksw_config *config, con= st char *key, * - sp_offset |so (u16) : offset from stack pointer at func_offset * - watch_len |wl (u16) : watch length (1,2,4,8) */ -static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *c= onfig) +static int ksw_parse_config(char *buf, struct ksw_config *config) { char *part, *key, *val; int ret; @@ -109,18 +113,89 @@ static int __maybe_unused ksw_parse_config(char *buf,= struct ksw_config *config) return 0; } =20 +static ssize_t kstackwatch_proc_write(struct file *file, + const char __user *buffer, size_t count, + loff_t *pos) +{ + char input[MAX_CONFIG_STR_LEN]; + int ret; + + if (count =3D=3D 0 || count >=3D sizeof(input)) + return -EINVAL; + + if (copy_from_user(input, buffer, count)) + return -EFAULT; + + input[count] =3D '\0'; + strim(input); + + if (!strlen(input)) { + pr_info("config cleared\n"); + return count; + } + + ret =3D ksw_parse_config(input, ksw_config); + if (ret) { + pr_err("Failed to parse config %d\n", ret); + return ret; + } + + return count; +} + +static int kstackwatch_proc_show(struct seq_file *m, void *v) +{ + seq_printf(m, "%s\n", ksw_config->user_input); + return 0; +} + +static int kstackwatch_proc_open(struct inode *inode, struct file *file) +{ + if (atomic_cmpxchg(&config_file_busy, 0, 1)) + return -EBUSY; + + return single_open(file, kstackwatch_proc_show, NULL); +} + +static int kstackwatch_proc_release(struct inode *inode, struct file *file) +{ + atomic_set(&config_file_busy, 0); + return single_release(inode, file); +} + +static const struct proc_ops kstackwatch_proc_ops =3D { + .proc_open =3D kstackwatch_proc_open, + .proc_read =3D seq_read, + .proc_write =3D kstackwatch_proc_write, + .proc_lseek =3D seq_lseek, + .proc_release =3D kstackwatch_proc_release, +}; + +const struct ksw_config *ksw_get_config(void) +{ + return ksw_config; +} static int __init kstackwatch_init(void) { ksw_config =3D kzalloc(sizeof(*ksw_config), GFP_KERNEL); if (!ksw_config) return -ENOMEM; =20 + if (!proc_create("kstackwatch", 0600, NULL, &kstackwatch_proc_ops)) { + pr_err("create proc kstackwatch fail"); + kfree(ksw_config); + return -ENOMEM; + } + pr_info("module loaded\n"); return 0; } =20 static void __exit kstackwatch_exit(void) { + remove_proc_entry("kstackwatch", NULL); + kfree(ksw_config->func_name); + kfree(ksw_config->user_input); kfree(ksw_config); =20 pr_info("module unloaded\n"); diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index a7bad207f863..983125d5cf18 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -29,4 +29,7 @@ struct ksw_config { char *user_input; }; =20 +// singleton, only modified in kernel.c +const struct ksw_config *ksw_get_config(void); + #endif /* _KSTACKWATCH_H */ --=20 2.43.0