From patchwork Tue Mar 19 09:53:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Slaby X-Patchwork-Id: 781491 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 1F1ED7D419; Tue, 19 Mar 2024 09:53:33 +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=1710842014; cv=none; b=o8sXyplJmzMO5CsyOPXW9MAJFsf0teRDScooH3tLxX4TdJ8ufYX0StrUCCgoChCWILSuxqCQ4aUlZzbCZRvQI49IE8CJpCVJgsj+xy5D1rKcuN8rim0kIBkxQNO8XC46f6pMlPkScpZWuDLYUN4gO6fH0J+OWxKM8Y5iKFPIDVQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710842014; c=relaxed/simple; bh=Y5yr2WoT18t+omb36hLfYnGJAHFNVuXaCL5M5ighc1g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hok/YEoghrZqv95yvn/mHO35OkR61qLvFXXedQ3rpGIL1RIorzrj3cINtnvBh5I6AWVnRK8HMgoJfY1GYgQ6kdm8Z0lYK0pNR4YvgtjRzg14ANqqkTvFJxrBv2xbv02ftLP3pISGWp+d6X+c6rv6oGdq5j0+gV0tHhfMQZ819IE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gXQj2wKW; 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="gXQj2wKW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 564B7C43394; Tue, 19 Mar 2024 09:53:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710842013; bh=Y5yr2WoT18t+omb36hLfYnGJAHFNVuXaCL5M5ighc1g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gXQj2wKW28B+ES+inRotEsdEFbGSdL+TtwMPNHPH6P37Qj9yVLvSLgfPuiLJ9vRAZ fhGXhUEwijAH1ZEp4Y5bfYj0k52fY/+bPDylqz9fKCfkaIUYfPaa1xq0dANadd5KOV C1ucYpD2NOSbxJWleQZVc98ilDNNxooGDToxANEwYSmNSdlKLFx0s+UTZI3yLKTKym /lHHfULsBEIwOouEmykKcuq3hCO9BFX58OuayuhawUjndhEXOB4ljCFMwx2/ikYTbW Fx1hHIALjjhbEmc69+y3vT+vI5J6wt/nVgsT+fYqu0w9o9fq/g+9xgJPJhKzccMX/O eN94KwvJXcIDQ== From: "Jiri Slaby (SUSE)" To: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Jiri Slaby (SUSE)" , Stefani Seibold , Andrew Morton Subject: [RFT 03/15] kfifo: add kfifo_out_linear{,_ptr}() Date: Tue, 19 Mar 2024 10:53:02 +0100 Message-ID: <20240319095315.27624-4-jirislaby@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240319095315.27624-1-jirislaby@kernel.org> References: <20240319095315.27624-1-jirislaby@kernel.org> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 --- Notes: [v2] * added Andrew's fix -- missing right parenthesis * simplify __kfifo_out_linear() -- min3() results can be returned directly. include/linux/kfifo.h | 63 +++++++++++++++++++++++++++++++++++++++++++ lib/kfifo.c | 26 ++++++++++++++++++ 2 files changed, 89 insertions(+) diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index 8f3369ec528b..3def70e1a3e3 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -827,6 +827,63 @@ __kfifo_uint_must_check_helper( \ }) \ ) +/** + * 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 = (fifo); \ + unsigned int *__tail = (tail); \ + unsigned long __n = (n); \ + const size_t __recsize = sizeof(*__tmp->rectype); \ + struct __kfifo *__kfifo = &__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 data 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 = (fifo); \ + unsigned int ___tail; \ + unsigned int ___n = kfifo_out_linear(___tmp, &___tail, (n)); \ + *(ptr) = ___tmp->kfifo.data + ___tail * kfifo_esize(___tmp); \ + ___n; \ +}) \ +) + + extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, size_t esize, gfp_t gfp_mask); @@ -856,6 +913,9 @@ extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo, extern unsigned int __kfifo_out_peek(struct __kfifo *fifo, void *buf, unsigned int len); +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); @@ -885,6 +945,9 @@ 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); +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); #endif diff --git a/lib/kfifo.c b/lib/kfifo.c index 958099cc4914..a36bfdbdb17d 100644 --- a/lib/kfifo.c +++ b/lib/kfifo.c @@ -163,6 +163,19 @@ unsigned int __kfifo_out_peek(struct __kfifo *fifo, } EXPORT_SYMBOL(__kfifo_out_peek); +unsigned int __kfifo_out_linear(struct __kfifo *fifo, + unsigned int *tail, unsigned int n) +{ + unsigned int size = fifo->mask + 1; + unsigned int off = fifo->out & fifo->mask; + + if (tail) + *tail = off; + + return min3(n, fifo->in - fifo->out, size - off); +} +EXPORT_SYMBOL(__kfifo_out_linear); + unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len) { @@ -473,6 +486,19 @@ unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf, } EXPORT_SYMBOL(__kfifo_out_peek_r); +unsigned int __kfifo_out_linear_r(struct __kfifo *fifo, + unsigned int *tail, unsigned int n, size_t recsize) +{ + if (fifo->in == fifo->out) + return 0; + + if (tail) + *tail = 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) {