* [PATCH] drivers/scsi/esas2r: Replace binary semaphore with mutex
@ 2019-11-01 20:51 Davidlohr Bueso
0 siblings, 0 replies; only message in thread
From: Davidlohr Bueso @ 2019-11-01 20:51 UTC (permalink / raw)
To: linuxdrivers, jejb, martin.petersen
Cc: linux-kernel, linux-scsi, dave, Davidlohr Bueso
At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal
than semaphores; it's also a nicer interface for mutual exclusion,
which is why they are encouraged over binary semaphores, when possible.
Replace the buffered_ioctl_sem, its semantics implies traditional lock
ownership; that is, the lock owner is the same for both lock/unlock
operations. Therefore it is safe to convert.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
This is in an effort to reduce semaphore users in the kernel.
Compile-tested only.
drivers/scsi/esas2r/esas2r_ioctl.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/esas2r/esas2r_ioctl.c b/drivers/scsi/esas2r/esas2r_ioctl.c
index 442c5e70a7b4..aad352fe27cf 100644
--- a/drivers/scsi/esas2r/esas2r_ioctl.c
+++ b/drivers/scsi/esas2r/esas2r_ioctl.c
@@ -56,7 +56,7 @@ dma_addr_t esas2r_buffered_ioctl_addr;
u32 esas2r_buffered_ioctl_size;
struct pci_dev *esas2r_buffered_ioctl_pcid;
-static DEFINE_SEMAPHORE(buffered_ioctl_semaphore);
+static DEFINE_MUTEX(buffered_ioctl_mutex);
typedef int (*BUFFERED_IOCTL_CALLBACK)(struct esas2r_adapter *,
struct esas2r_request *,
struct esas2r_sg_context *,
@@ -209,7 +209,7 @@ static u8 handle_buffered_ioctl(struct esas2r_buffered_ioctl *bi)
struct esas2r_sg_context sgc;
u8 result = IOCTL_SUCCESS;
- if (down_interruptible(&buffered_ioctl_semaphore))
+ if (mutex_lock_interruptible(&buffered_ioctl_mutex))
return IOCTL_OUT_OF_RESOURCES;
/* allocate a buffer or use the existing buffer. */
@@ -285,7 +285,7 @@ static u8 handle_buffered_ioctl(struct esas2r_buffered_ioctl *bi)
if (result == IOCTL_SUCCESS)
memcpy(bi->ioctl, esas2r_buffered_ioctl, bi->length);
- up(&buffered_ioctl_semaphore);
+ mutex_unlock(&buffered_ioctl_mutex);
return result;
}
--
2.16.4
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