From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> To: stefan.wahren@i2se.com, eric@anholt.net, dave.stevenson@raspberrypi.org Cc: nsaenzjulienne@suse.de, linux-rpi-kernel@lists.infradead.org, gregkh@linuxfoundation.org, linux-arm-kernel@lists.infradead.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC 12/18] staging: vchiq_util: use completions instead of semaphores Date: Fri, 26 Oct 2018 15:48:07 +0200 [thread overview] Message-ID: <20181026134813.7775-13-nsaenzjulienne@suse.de> (raw) In-Reply-To: <20181026134813.7775-1-nsaenzjulienne@suse.de> It is preferred in the kernel to avoid using semaphores to wait for events, as they are optimised for the opposite situation; where the common case is that they are available and may block only occasionally. FYI see this thread: https://lkml.org/lkml/2008/4/11/323. Also completions are semantically more explicit in this case. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> --- .../interface/vchiq_arm/vchiq_util.c | 16 ++++++++-------- .../interface/vchiq_arm/vchiq_util.h | 6 +++--- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c index 2e52f07bbaa9..44b954daa74a 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -48,8 +48,8 @@ int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size) queue->write = 0; queue->initialized = 1; - sema_init(&queue->pop, 0); - sema_init(&queue->push, 0); + init_completion(&queue->pop); + init_completion(&queue->push); queue->storage = kcalloc(size, sizeof(VCHIQ_HEADER_T *), GFP_KERNEL); if (!queue->storage) { @@ -80,7 +80,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) return; while (queue->write == queue->read + queue->size) { - if (down_interruptible(&queue->pop) != 0) + if (wait_for_completion_interruptible(&queue->pop)) flush_signals(current); } @@ -100,17 +100,17 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) queue->write++; - up(&queue->push); + complete(&queue->push); } VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) { while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } - up(&queue->push); // We haven't removed anything from the queue. + complete(&queue->push); // We haven't removed anything from the queue. /* * Read from queue->storage must be visible after read from @@ -126,7 +126,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) VCHIQ_HEADER_T *header; while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } @@ -146,7 +146,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) queue->read++; - up(&queue->pop); + complete(&queue->pop); return header; } diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h index 5a1540d349d3..b226227fe5bc 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h @@ -35,7 +35,7 @@ #define VCHIQ_UTIL_H #include <linux/types.h> -#include <linux/semaphore.h> +#include <linux/completion.h> #include <linux/mutex.h> #include <linux/bitops.h> #include <linux/kthread.h> @@ -60,8 +60,8 @@ typedef struct { int write; int initialized; - struct semaphore pop; - struct semaphore push; + struct completion pop; + struct completion push; VCHIQ_HEADER_T **storage; } VCHIU_QUEUE_T; -- 2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: nsaenzjulienne@suse.de (Nicolas Saenz Julienne) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH RFC 12/18] staging: vchiq_util: use completions instead of semaphores Date: Fri, 26 Oct 2018 15:48:07 +0200 [thread overview] Message-ID: <20181026134813.7775-13-nsaenzjulienne@suse.de> (raw) In-Reply-To: <20181026134813.7775-1-nsaenzjulienne@suse.de> It is preferred in the kernel to avoid using semaphores to wait for events, as they are optimised for the opposite situation; where the common case is that they are available and may block only occasionally. FYI see this thread: https://lkml.org/lkml/2008/4/11/323. Also completions are semantically more explicit in this case. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> --- .../interface/vchiq_arm/vchiq_util.c | 16 ++++++++-------- .../interface/vchiq_arm/vchiq_util.h | 6 +++--- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c index 2e52f07bbaa9..44b954daa74a 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -48,8 +48,8 @@ int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size) queue->write = 0; queue->initialized = 1; - sema_init(&queue->pop, 0); - sema_init(&queue->push, 0); + init_completion(&queue->pop); + init_completion(&queue->push); queue->storage = kcalloc(size, sizeof(VCHIQ_HEADER_T *), GFP_KERNEL); if (!queue->storage) { @@ -80,7 +80,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) return; while (queue->write == queue->read + queue->size) { - if (down_interruptible(&queue->pop) != 0) + if (wait_for_completion_interruptible(&queue->pop)) flush_signals(current); } @@ -100,17 +100,17 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) queue->write++; - up(&queue->push); + complete(&queue->push); } VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) { while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } - up(&queue->push); // We haven't removed anything from the queue. + complete(&queue->push); // We haven't removed anything from the queue. /* * Read from queue->storage must be visible after read from @@ -126,7 +126,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) VCHIQ_HEADER_T *header; while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } @@ -146,7 +146,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) queue->read++; - up(&queue->pop); + complete(&queue->pop); return header; } diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h index 5a1540d349d3..b226227fe5bc 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h @@ -35,7 +35,7 @@ #define VCHIQ_UTIL_H #include <linux/types.h> -#include <linux/semaphore.h> +#include <linux/completion.h> #include <linux/mutex.h> #include <linux/bitops.h> #include <linux/kthread.h> @@ -60,8 +60,8 @@ typedef struct { int write; int initialized; - struct semaphore pop; - struct semaphore push; + struct completion pop; + struct completion push; VCHIQ_HEADER_T **storage; } VCHIU_QUEUE_T; -- 2.19.1
next prev parent reply other threads:[~2018-10-26 13:48 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-10-26 13:47 [PATCH RFC 00/18] staging: vchiq: remove dead code & misc fixes Nicolas Saenz Julienne 2018-10-26 13:47 ` Nicolas Saenz Julienne 2018-10-26 13:47 ` [PATCH RFC 01/18] staging: vchiq_core: rework vchiq_get_config Nicolas Saenz Julienne 2018-10-26 13:47 ` Nicolas Saenz Julienne 2018-10-26 13:47 ` [PATCH RFC 02/18] staging: vchiq_arm: rework close/remove_service IOCTLS Nicolas Saenz Julienne 2018-10-26 13:47 ` Nicolas Saenz Julienne 2018-10-26 13:47 ` [PATCH RFC 03/18] staging: vchiq_shim: delete vchi_service_create Nicolas Saenz Julienne 2018-10-26 13:47 ` Nicolas Saenz Julienne 2018-10-26 13:47 ` [PATCH RFC 04/18] stagning: vchiq_arm: use list_for_each_entry when accessing bulk_waiter_list Nicolas Saenz Julienne 2018-10-26 13:47 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 05/18] staging: vchiq_arm: get rid of vchi_mh.h Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 06/18] staging: vchiq_arm: rework vchiq_ioc_copy_element_data Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 07/18] staging: vchiq-core: get rid of is_master distinction Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 08/18] staging: vchiq_core: remove unnecessary safety checks in vchiq_init_state Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 09/18] staging: vchiq_core: do not initialize semaphores twice Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-28 20:45 ` Stefan Wahren 2018-10-28 20:45 ` Stefan Wahren 2018-11-06 15:41 ` Nicolas Saenz Julienne 2018-11-06 15:41 ` Nicolas Saenz Julienne 2018-11-06 16:06 ` Stefan Wahren 2018-11-06 16:06 ` Stefan Wahren 2018-11-06 18:28 ` Nicolas Saenz Julienne 2018-11-06 18:28 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 10/18] staging: vchiq_core: don't add a wmb() before remote_event_signal() Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 11/18] staging: vchiq_arm: use completions instead of semaphores Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-28 21:00 ` Stefan Wahren 2018-10-28 21:00 ` Stefan Wahren 2018-10-26 13:48 ` Nicolas Saenz Julienne [this message] 2018-10-26 13:48 ` [PATCH RFC 12/18] staging: vchiq_util: " Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 13/18] staging: vchiq_core: " Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 14/18] staging: vchiq_util: get rid of unneeded memory barriers Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 15/18] stagning: vchiq_core: fix logic redundancy in parse_open Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-28 20:58 ` Stefan Wahren 2018-10-28 20:58 ` Stefan Wahren 2018-10-26 13:48 ` [PATCH RFC 16/18] staging: vchiq_arm: rework probe and init functions Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-28 21:02 ` Stefan Wahren 2018-10-28 21:02 ` Stefan Wahren 2018-10-26 13:48 ` [PATCH RFC 17/18] staging: vchiq_arm: fix open/release cdev functions Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-26 13:48 ` [PATCH RFC 18/18] staging: vchiq: add more tasks to the TODO list Nicolas Saenz Julienne 2018-10-26 13:48 ` Nicolas Saenz Julienne 2018-10-28 21:11 ` Stefan Wahren 2018-10-28 21:11 ` Stefan Wahren
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