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mtip32xx: avoid using semaphores 

The "cmd_slot_unal" semaphore is never used in a blocking way
but only as an atomic counter. Change the code to using
atomic_dec_if_positive() as a better API.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Arnd Bergmann 2018-12-10 22:34:39 +01:00 committed by Jens Axboe
parent 6f75723190
commit e4025e46f0
2 changed files with 5 additions and 5 deletions
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6
drivers/block/mtip32xx/mtip32xx.c
View File

@ -2680,7 +2680,7 @@ static void mtip_softirq_done_fn(struct request *rq)
cmd->direction); cmd->direction);
if (unlikely(cmd->unaligned)) if (unlikely(cmd->unaligned))
up(&dd->port->cmd_slot_unal); atomic_inc(&dd->port->cmd_slot_unal);
blk_mq_end_request(rq, cmd->status); blk_mq_end_request(rq, cmd->status);
} }
@ -2990,7 +2990,7 @@ static int mtip_hw_init(struct driver_data *dd)
else else
dd->unal_qdepth = 0; dd->unal_qdepth = 0;
sema_init(&dd->port->cmd_slot_unal, dd->unal_qdepth); atomic_set(&dd->port->cmd_slot_unal, dd->unal_qdepth);
/* Spinlock to prevent concurrent issue */ /* Spinlock to prevent concurrent issue */
for (i = 0; i < MTIP_MAX_SLOT_GROUPS; i++) for (i = 0; i < MTIP_MAX_SLOT_GROUPS; i++)
@ -3533,7 +3533,7 @@ static bool mtip_check_unal_depth(struct blk_mq_hw_ctx *hctx,
cmd->unaligned = 1; cmd->unaligned = 1;
} }
if (cmd->unaligned && down_trylock(&dd->port->cmd_slot_unal)) if (cmd->unaligned && atomic_dec_if_positive(&dd->port->cmd_slot_unal) >= 0)
return true; return true;
return false; return false;

4
drivers/block/mtip32xx/mtip32xx.h
View File

@ -433,8 +433,8 @@ struct mtip_port {
*/ */
unsigned long ic_pause_timer; unsigned long ic_pause_timer;
/* Semaphore to control queue depth of unaligned IOs */ /* Counter to control queue depth of unaligned IOs */
struct semaphore cmd_slot_unal; atomic_t cmd_slot_unal;
/* Spinlock for working around command-issue bug. */ /* Spinlock for working around command-issue bug. */
spinlock_t cmd_issue_lock[MTIP_MAX_SLOT_GROUPS]; spinlock_t cmd_issue_lock[MTIP_MAX_SLOT_GROUPS];