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
next prev parent reply other threads:[~2018-10-26 13:48 UTC|newest]
Thread overview: 27+ 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 ` [PATCH RFC 01/18] staging: vchiq_core: rework vchiq_get_config 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 ` [PATCH RFC 03/18] staging: vchiq_shim: delete vchi_service_create 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 13:48 ` [PATCH RFC 05/18] staging: vchiq_arm: get rid of vchi_mh.h 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 ` [PATCH RFC 07/18] staging: vchiq-core: get rid of is_master distinction 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 ` [PATCH RFC 09/18] staging: vchiq_core: do not initialize semaphores twice Nicolas Saenz Julienne
2018-10-28 20:45 ` Stefan Wahren
2018-11-06 15:41 ` Nicolas Saenz Julienne
2018-11-06 16:06 ` Stefan Wahren
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 ` [PATCH RFC 11/18] staging: vchiq_arm: use completions instead of semaphores Nicolas Saenz Julienne
2018-10-28 21:00 ` Stefan Wahren
2018-10-26 13:48 ` Nicolas Saenz Julienne [this message]
2018-10-26 13:48 ` [PATCH RFC 13/18] staging: vchiq_core: " 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 ` [PATCH RFC 15/18] stagning: vchiq_core: fix logic redundancy in parse_open Nicolas Saenz Julienne
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
2018-10-28 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 ` [PATCH RFC 18/18] staging: vchiq: add more tasks to the TODO list Nicolas Saenz Julienne
2018-10-28 21:11 ` Stefan Wahren
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