From nobody Fri Dec 19 17:34:21 2025 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 852AF7C6D4 for ; Fri, 23 Feb 2024 11:52:03 +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=1708689123; cv=none; b=gitFHneDKf1+QgzLZVyHVEWz2G/Qq20ITataIJXr/4Af+0LdfMtL4QqutAiWPue7COOGvPzQONJzah7RMysiAIFOnIpzQcfoGfY60UPtzOv47zJftPR60v8NrW7PwBqpQ/RpJHh/8jPncLsIs4ToeWmicVnUNfv1w+UVrnLRAHM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708689123; c=relaxed/simple; bh=deFyJ8OYCh9my5qGUB1HBB8ENRS08AcwthOwt9dAcZE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FzmTdi77LsUY8EXKCBQ83x0BXRjjylwf6k47Ab7AJ72+QfG7JIS4UUoXKROHyqqIHGbgXnVoVX9duUVhBHyQwFp2P6D2fz8wHsIG0cfI3GGhc3itGAkK8KW41D7YODcFd5mdTqLBT6vpM6A+X1jknBzCEDBTLUn6S9GcnN2spuk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sLd5+eve; 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="sLd5+eve" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1121EC433A6; Fri, 23 Feb 2024 11:52:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708689123; bh=deFyJ8OYCh9my5qGUB1HBB8ENRS08AcwthOwt9dAcZE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sLd5+eve5ubmzq9nTyF7ESHZMUlcMXxv05amHg2Rgc92mjiTnyQPPKHm7rPcYdj5e 87uRTDAp3Ts8f+3vRroeBLRPc7dfESbMBKq7T07EwVazD0zr3ulios1+BO9/7bJ+Xp tyhJZ9QZ8tuul99NMOLafsw0nURZ38ZqF6Kxzz7nHUyLqNFPkhw9eryeJwkrCAYXjX JvLqIYFaJTo41cZb5nr/ep6eENsSFNRFCB9eTZMwGS4bD07UlHMfTRKCJkyf+OjC5P OTCeDvJuWJw5gcBvX3EyNZfGGx9n8g7z3lEhEfRDVK5U+50AtGkE9Jf83s0wV8DUNS CcFuuJv3T0aYg== From: "Jiri Slaby (SUSE)" To: stefani@seibold.net Cc: linux-kernel@vger.kernel.org, "Jiri Slaby (SUSE)" , Andrew Morton Subject: [PATCH 3/4] kfifo: add kfifo_out_linear{,_ptr}() Date: Fri, 23 Feb 2024 12:51:54 +0100 Message-ID: <20240223115155.8806-4-jirislaby@kernel.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240223115155.8806-1-jirislaby@kernel.org> References: <20240223115155.8806-1-jirislaby@kernel.org> 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" These are helpers which are going to be used in the serial layer. We need a wrapper around kfifo which provides us with a tail (sometimes "tail" offset, sometimes a pointer) to the kfifo data. And which returns count of available data -- but not larger than to the end of the buffer (hence _linear in the names). I.e. something like CIRC_CNT_TO_END() in the legacy circ_buf. This patch adds such two helpers. Signed-off-by: Jiri Slaby (SUSE) Cc: Stefani Seibold Cc: Andrew Morton --- include/linux/kfifo.h | 64 +++++++++++++++++++++++++++++++++++++++++++ lib/kfifo.c | 28 +++++++++++++++++++ 2 files changed, 92 insertions(+) diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index 9e64eb03c535..0491bc526240 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -827,6 +827,64 @@ __kfifo_uint_must_check_helper( \ }) \ ) =20 +/** + * kfifo_out_linear - gets a tail of/offset to available data + * @fifo: address of the fifo to be used + * @tail: pointer to an unsigned int to store the value of tail + * @n: max. number of elements to point at + * + * This macro obtains the offset (tail) to the available data in the fifo + * buffer and returns the + * numbers of elements available. It returns the available count till the = end + * of data or till the end of the buffer. So that it can be used for linear + * data processing (like memcpy() of (@fifo->data + @tail) with count + * returned). + * + * Note that with only one concurrent reader and one concurrent + * writer, you don't need extra locking to use these macro. + */ +#define kfifo_out_linear(fifo, tail, n) \ +__kfifo_uint_must_check_helper( \ +({ \ + typeof((fifo) + 1) __tmp =3D (fifo); \ + unsigned int *__tail =3D (tail); \ + unsigned long __n =3D (n); \ + const size_t __recsize =3D sizeof(*__tmp->rectype); \ + struct __kfifo *__kfifo =3D &__tmp->kfifo; \ + (__recsize) ? \ + __kfifo_out_linear_r(__kfifo, __tail, __n, __recsize) : \ + __kfifo_out_linear(__kfifo, __tail, __n); \ +}) \ +) + +/** + * kfifo_out_linear_ptr - gets a pointer to the available data + * @fifo: address of the fifo to be used + * @ptr: pointer to data to store the pointer to tail + * @n: max. number of elements to point at + * + * Similarly to kfifo_out_linear(), this macro obtains the pointer to the + * available data in the fifo buffer and returns the numbers of elements + * available. It returns the available count till the end of available dat= a or + * till the end of the buffer. So that it can be used for linear data + * processing (like memcpy() of @ptr with count returned). + * + * Note that with only one concurrent reader and one concurrent + * writer, you don't need extra locking to use these macro. + */ +#define kfifo_out_linear_ptr(fifo, ptr, n) \ +__kfifo_uint_must_check_helper( \ +({ \ + typeof((fifo) + 1) ___tmp =3D (fifo); \ + unsigned int ___tail; \ + unsigned int ___n =3D kfifo_out_linear(___tmp, &___tail, (n)); \ + struct __kfifo *___kfifo =3D &___tmp->kfifo; \ + *(ptr) =3D ___kfifo->data + ___tail * kfifo_esize(___tmp); \ + ___n; \ +}) \ +) + + extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, size_t esize, gfp_t gfp_mask); =20 @@ -856,6 +914,9 @@ extern unsigned int __kfifo_dma_out_prepare(struct __kf= ifo *fifo, extern unsigned int __kfifo_out_peek(struct __kfifo *fifo, void *buf, unsigned int len); =20 +extern unsigned int __kfifo_out_linear(struct __kfifo *fifo, + unsigned int *tail, unsigned int n); + extern unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf, unsigned int len, size_t recsize); =20 @@ -885,6 +946,9 @@ extern void __kfifo_skip_r(struct __kfifo *fifo, size_t= recsize); extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, unsigned int len, size_t recsize); =20 +extern unsigned int __kfifo_out_linear_r(struct __kfifo *fifo, + unsigned int *tail, unsigned int n, size_t recsize); + extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize); =20 #endif diff --git a/lib/kfifo.c b/lib/kfifo.c index 958099cc4914..9f1d8f68deb8 100644 --- a/lib/kfifo.c +++ b/lib/kfifo.c @@ -163,6 +163,21 @@ unsigned int __kfifo_out_peek(struct __kfifo *fifo, } EXPORT_SYMBOL(__kfifo_out_peek); =20 +unsigned int __kfifo_out_linear(struct __kfifo *fifo, + unsigned int *tail, unsigned int n) +{ + unsigned int size =3D fifo->mask + 1; + unsigned int off =3D fifo->out & fifo->mask; + + n =3D min3(n, fifo->in - fifo->out, size - off); + + if (tail) + *tail =3D off; + + return n; +} +EXPORT_SYMBOL(__kfifo_out_linear); + unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len) { @@ -473,6 +488,19 @@ unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, = void *buf, } EXPORT_SYMBOL(__kfifo_out_peek_r); =20 +unsigned int __kfifo_out_linear_r(struct __kfifo *fifo, + unsigned int *tail, unsigned int n, size_t recsize) +{ + if (fifo->in =3D=3D fifo->out) + return 0; + + if (tail) + *tail =3D fifo->out + recsize; + + return min(n, __kfifo_peek_n(fifo, recsize); +} +EXPORT_SYMBOL(__kfifo_out_linear_r); + unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf, unsigned int len, size_t recsize) { --=20 2.43.2