From: Arnd Bergmann <arnd@arndb.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>,
Johannes Thumshirn <jthumshirn@suse.de>,
Hannes Reinecke <hare@suse.de>,
Bart Van Assche <bvanassche@acm.org>,
Matthew Wilcox <willy@infradead.org>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mtip32xx: avoid using semaphores
Date: Mon, 10 Dec 2018 22:34:39 +0100 [thread overview]
Message-ID: <20181210213459.1147671-1-arnd@arndb.de> (raw)
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>
---
drivers/block/mtip32xx/mtip32xx.c | 6 +++---
drivers/block/mtip32xx/mtip32xx.h | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 2b0ac9d01e51..d7dc307d0cc8 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -2680,7 +2680,7 @@ static void mtip_softirq_done_fn(struct request *rq)
cmd->direction);
if (unlikely(cmd->unaligned))
- up(&dd->port->cmd_slot_unal);
+ atomic_inc(&dd->port->cmd_slot_unal);
blk_mq_end_request(rq, cmd->status);
}
@@ -2990,7 +2990,7 @@ static int mtip_hw_init(struct driver_data *dd)
else
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 */
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;
}
- 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 false;
diff --git a/drivers/block/mtip32xx/mtip32xx.h b/drivers/block/mtip32xx/mtip32xx.h
index c33f8c3d9fb4..abce25f27f57 100644
--- a/drivers/block/mtip32xx/mtip32xx.h
+++ b/drivers/block/mtip32xx/mtip32xx.h
@@ -433,8 +433,8 @@ struct mtip_port {
*/
unsigned long ic_pause_timer;
- /* Semaphore to control queue depth of unaligned IOs */
- struct semaphore cmd_slot_unal;
+ /* Counter to control queue depth of unaligned IOs */
+ atomic_t cmd_slot_unal;
/* Spinlock for working around command-issue bug. */
spinlock_t cmd_issue_lock[MTIP_MAX_SLOT_GROUPS];
--
2.20.0
next reply other threads:[~2018-12-10 21:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-10 21:34 Arnd Bergmann [this message]
2018-12-10 21:44 ` [PATCH] mtip32xx: avoid using semaphores Jens Axboe
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