Re: [PATCH] Introduce down_try() so we can move away from down_trylock()

From: Rusty Russell
Date: Mon Aug 04 2008 - 03:57:36 EST

On Monday 04 August 2008 15:53:59 Linus Torvalds wrote:
> On Mon, 4 Aug 2008, Rusty Russell wrote:
> > Someone sent me a patch documenting the illogic of down_trylock(). I
> > decided to try to fix it rather than just bitch and moan.
>
> I do agree that it is illogical. I just think your solution is worse than
> the problem - turning one illogical function into a redundant one seems
> the worse problem.

Ah, to be clear: my second patch switches down_trylock() in terms of
down_try() and deprecates it. Then 21 replacement patches. Then finally a
patch to remove down_trylock() altogether.

This was "minimal obviously correct" patch.

> I'm much happier telling people to "just don't use semaphores any more".
> The _legacy_ users get down_trylock() right.

It just annoys me to see a turd in the tree. Even a little old one.

Thanks,
Rusty.

Here's the git tree if anyone feels enthused (without final removal patch):

The following changes since commit 2b12a4c524812fb3f6ee590a02e65b95c8c32229:
Linus Torvalds (1):
Merge branch 'release' of git://git.kernel.org/.../aegl/linux-2.6

are available in the git repository at:

ssh://master.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus.git master

Rusty Russell (24):
Introduce down_try()
Deprecate down_trylock()
down_trylock -> down_try in documentation and comments.
down_trylock -> down_try in arch/ia64/kernel/salinfo.c
down_trylock -> down_try in drivers/char/snsc.c
down_trylock -> down_try in drivers/char/viotape.c
down_trylock -> down_try in drivers/infiniband/core/user_mad.c
down_trylock -> down_try in drivers/input/serio/hil_mlc.c
down_trylock -> down_try in drivers/input/serio/hp_sdc_mlc.c
down_trylock -> down_try in drivers/md/dm-raid1.c
down_trylock -> down_try in drivers/net/3c527.c
down_trylock -> down_try in drivers/net/irda/sir_dev.c
down_trylock -> down_try in drivers/net/wireless/airo.c
down_trylock -> down_try in drivers/scsi/aacraid/commsup.c
down_trylock -> down_try for usb_trylock_device()
down_trylock -> down_try in drivers/usb/gadget/inode.c
down_trylock -> down_try in xfs
down_trylock -> down_try in kernel/printk.c
down_trylock -> down_try in drivers/watchdog/ar7_wdt.c
down_trylock -> down_try in drivers/watchdog/it8712f_wdt.c
down_trylock -> down_try in drivers/watchdog/s3c2410_wdt.c
down_trylock -> down_try in drivers/watchdog/sc1200wdt.c
down_trylock -> down_try in drivers/watchdog/scx200_wdt.c
down_trylock -> down_try in drivers/watchdog/wdt_pci.c

arch/ia64/kernel/salinfo.c | 4 ++--
drivers/char/snsc.c | 4 ++--
drivers/char/viotape.c | 4 ++--
drivers/infiniband/core/user_mad.c | 2 +-
drivers/input/serio/hil_mlc.c | 4 ++--
drivers/input/serio/hp_sdc_mlc.c | 14 +++++++-------
drivers/md/dm-raid1.c | 2 +-
drivers/net/3c527.c | 2 +-
drivers/net/irda/sir_dev.c | 2 +-
drivers/net/wireless/airo.c | 12 ++++++------
drivers/scsi/aacraid/commsup.c | 2 +-
drivers/usb/core/usb.c | 2 +-
drivers/usb/gadget/inode.c | 2 +-
drivers/watchdog/ar7_wdt.c | 2 +-
drivers/watchdog/it8712f_wdt.c | 2 +-
drivers/watchdog/s3c2410_wdt.c | 2 +-
drivers/watchdog/sc1200wdt.c | 2 +-
drivers/watchdog/scx200_wdt.c | 2 +-
drivers/watchdog/wdt_pci.c | 2 +-
fs/ocfs2/inode.c | 4 ----
fs/xfs/linux-2.6/sema.h | 8 +++-----
fs/xfs/linux-2.6/xfs_buf.c | 4 ++--
include/linux/mutex.h | 4 ----
include/linux/semaphore.h | 8 ++++++--
include/linux/usb.h | 2 +-
kernel/mutex.c | 4 ++--
kernel/printk.c | 4 ++--
kernel/semaphore.c | 17 ++++++++---------
28 files changed, 58 insertions(+), 65 deletions(-)
===
diff --git a/arch/ia64/kernel/salinfo.c b/arch/ia64/kernel/salinfo.c
index ecb9eb7..57c10ef 100644
--- a/arch/ia64/kernel/salinfo.c
+++ b/arch/ia64/kernel/salinfo.c
@@ -192,7 +192,7 @@ struct salinfo_platform_oemdata_parms {
static void
salinfo_work_to_do(struct salinfo_data *data)
{
- down_trylock(&data->mutex);
+ down_try(&data->mutex);
up(&data->mutex);
}

@@ -309,7 +309,7 @@ salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t
int i, n, cpu = -1;

retry:
- if (cpus_empty(data->cpu_event) && down_trylock(&data->mutex)) {
+ if (cpus_empty(data->cpu_event) && !down_try(&data->mutex)) {
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
if (down_interruptible(&data->mutex))
diff --git a/drivers/char/snsc.c b/drivers/char/snsc.c
index 3ce60df..548161d 100644
--- a/drivers/char/snsc.c
+++ b/drivers/char/snsc.c
@@ -164,7 +164,7 @@ scdrv_read(struct file *file, char __user *buf, size_t count, loff_t *f_pos)
struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

/* try to get control of the read buffer */
- if (down_trylock(&sd->sd_rbs)) {
+ if (!down_try(&sd->sd_rbs)) {
/* somebody else has it now;
* if we're non-blocking, then exit...
*/
@@ -256,7 +256,7 @@ scdrv_write(struct file *file, const char __user *buf,
struct subch_data_s *sd = (struct subch_data_s *) file->private_data;

/* try to get control of the write buffer */
- if (down_trylock(&sd->sd_wbs)) {
+ if (!down_try(&sd->sd_wbs)) {
/* somebody else has it now;
* if we're non-blocking, then exit...
*/
diff --git a/drivers/char/viotape.c b/drivers/char/viotape.c
index 7a70a40..884613e 100644
--- a/drivers/char/viotape.c
+++ b/drivers/char/viotape.c
@@ -362,7 +362,7 @@ static ssize_t viotap_write(struct file *file, const char *buf,
* semaphore
*/
if (noblock) {
- if (down_trylock(&reqSem)) {
+ if (!down_try(&reqSem)) {
ret = -EWOULDBLOCK;
goto free_op;
}
@@ -452,7 +452,7 @@ static ssize_t viotap_read(struct file *file, char *buf, size_t count,
* semaphore
*/
if (noblock) {
- if (down_trylock(&reqSem)) {
+ if (!down_try(&reqSem)) {
ret = -EWOULDBLOCK;
goto free_op;
}
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 268a2d2..ae7a981 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -901,7 +901,7 @@ static int ib_umad_sm_open(struct inode *inode, struct file *filp)
return -ENXIO;

if (filp->f_flags & O_NONBLOCK) {
- if (down_trylock(&port->sm_sem)) {
+ if (!down_try(&port->sm_sem)) {
ret = -EAGAIN;
goto fail;
}
diff --git a/drivers/input/serio/hil_mlc.c b/drivers/input/serio/hil_mlc.c
index 37586a6..e779f3d 100644
--- a/drivers/input/serio/hil_mlc.c
+++ b/drivers/input/serio/hil_mlc.c
@@ -607,7 +607,7 @@ static inline void hilse_setup_input(hil_mlc *mlc, const struct hilse_node *node
do_gettimeofday(&(mlc->instart));
mlc->icount = 15;
memset(mlc->ipacket, 0, 16 * sizeof(hil_packet));
- BUG_ON(down_trylock(&mlc->isem));
+ BUG_ON(!down_try(&mlc->isem));
}

#ifdef HIL_MLC_DEBUG
@@ -694,7 +694,7 @@ static int hilse_donode(hil_mlc *mlc)
out2:
write_unlock_irqrestore(&mlc->lock, flags);

- if (down_trylock(&mlc->osem)) {
+ if (!down_try(&mlc->osem)) {
nextidx = HILSEN_DOZE;
break;
}
diff --git a/drivers/input/serio/hp_sdc_mlc.c b/drivers/input/serio/hp_sdc_mlc.c
index b587e2d..e88a352 100644
--- a/drivers/input/serio/hp_sdc_mlc.c
+++ b/drivers/input/serio/hp_sdc_mlc.c
@@ -148,7 +148,7 @@ static int hp_sdc_mlc_in(hil_mlc *mlc, suseconds_t timeout)
priv = mlc->priv;

/* Try to down the semaphore */
- if (down_trylock(&mlc->isem)) {
+ if (!down_try(&mlc->isem)) {
struct timeval tv;
if (priv->emtestmode) {
mlc->ipacket[0] =
@@ -186,13 +186,13 @@ static int hp_sdc_mlc_cts(hil_mlc *mlc)
priv = mlc->priv;

/* Try to down the semaphores -- they should be up. */
- BUG_ON(down_trylock(&mlc->isem));
- BUG_ON(down_trylock(&mlc->osem));
+ BUG_ON(!down_try(&mlc->isem));
+ BUG_ON(!down_try(&mlc->osem));

up(&mlc->isem);
up(&mlc->osem);

- if (down_trylock(&mlc->csem)) {
+ if (!down_try(&mlc->csem)) {
if (priv->trans.act.semaphore != &mlc->csem)
goto poll;
else
@@ -229,7 +229,7 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
priv = mlc->priv;

/* Try to down the semaphore -- it should be up. */
- BUG_ON(down_trylock(&mlc->osem));
+ BUG_ON(!down_try(&mlc->osem));

if (mlc->opacket & HIL_DO_ALTER_CTRL)
goto do_control;
@@ -240,7 +240,7 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
return;
}
/* Shouldn't be sending commands when loop may be busy */
- BUG_ON(down_trylock(&mlc->csem));
+ BUG_ON(!down_try(&mlc->csem));
up(&mlc->csem);

priv->trans.actidx = 0;
@@ -296,7 +296,7 @@ static void hp_sdc_mlc_out(hil_mlc *mlc)
priv->tseq[3] = 0;
if (mlc->opacket & HIL_CTRL_APE) {
priv->tseq[3] |= HP_SDC_LPC_APE_IPF;
- down_trylock(&mlc->csem);
+ down_try(&mlc->csem);
}
enqueue:
hp_sdc_enqueue_transaction(&priv->trans);
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index ff05fe8..137f024 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -587,7 +587,7 @@ static void rh_recovery_prepare(struct region_hash *rh)
/* Extra reference to avoid race with rh_stop_recovery */
atomic_inc(&rh->recovery_in_flight);

- while (!down_trylock(&rh->recovery_count)) {
+ while (down_try(&rh->recovery_count)) {
atomic_inc(&rh->recovery_in_flight);
if (__rh_recovery_prepare(rh) <= 0) {
atomic_dec(&rh->recovery_in_flight);
diff --git a/drivers/net/3c527.c b/drivers/net/3c527.c
index 6aca0c6..9f57863 100644
--- a/drivers/net/3c527.c
+++ b/drivers/net/3c527.c
@@ -576,7 +576,7 @@ static int mc32_command_nowait(struct net_device *dev, u16 cmd, void *data, int
int ioaddr = dev->base_addr;
int ret = -1;

- if (down_trylock(&lp->cmd_mutex) == 0)
+ if (down_try(&lp->cmd_mutex))
{
lp->cmd_nonblocking=1;
lp->exec_box->mbox=0;
diff --git a/drivers/net/irda/sir_dev.c b/drivers/net/irda/sir_dev.c
index 3f32909..8b9e26e 100644
--- a/drivers/net/irda/sir_dev.c
+++ b/drivers/net/irda/sir_dev.c
@@ -287,7 +287,7 @@ int sirdev_schedule_request(struct sir_dev *dev, int initial_state, unsigned par
IRDA_DEBUG(2, "%s - state=0x%04x / param=%u\n", __func__,
initial_state, param);

- if (down_trylock(&fsm->sem)) {
+ if (!down_try(&fsm->sem)) {
if (in_interrupt() || in_atomic() || irqs_disabled()) {
IRDA_DEBUG(1, "%s(), state machine busy!\n", __func__);
return -EWOULDBLOCK;
diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index b5cd850..fc36977 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -2137,7 +2137,7 @@ static int airo_start_xmit(struct sk_buff *skb, struct net_device *dev) {
fids[i] |= (len << 16);
priv->xmit.skb = skb;
priv->xmit.fid = i;
- if (down_trylock(&priv->sem) != 0) {
+ if (!down_try(&priv->sem)) {
set_bit(FLAG_PENDING_XMIT, &priv->flags);
netif_stop_queue(dev);
set_bit(JOB_XMIT, &priv->jobs);
@@ -2208,7 +2208,7 @@ static int airo_start_xmit11(struct sk_buff *skb, struct net_device *dev) {
fids[i] |= (len << 16);
priv->xmit11.skb = skb;
priv->xmit11.fid = i;
- if (down_trylock(&priv->sem) != 0) {
+ if (!down_try(&priv->sem)) {
set_bit(FLAG_PENDING_XMIT11, &priv->flags);
netif_stop_queue(dev);
set_bit(JOB_XMIT11, &priv->jobs);
@@ -2258,7 +2258,7 @@ static struct net_device_stats *airo_get_stats(struct net_device *dev)

if (!test_bit(JOB_STATS, &local->jobs)) {
/* Get stats out of the card if available */
- if (down_trylock(&local->sem) != 0) {
+ if (!down_try(&local->sem)) {
set_bit(JOB_STATS, &local->jobs);
wake_up_interruptible(&local->thr_wait);
} else
@@ -2285,7 +2285,7 @@ static void airo_set_multicast_list(struct net_device *dev) {

if ((dev->flags ^ ai->flags) & IFF_PROMISC) {
change_bit(FLAG_PROMISC, &ai->flags);
- if (down_trylock(&ai->sem) != 0) {
+ if (!down_try(&ai->sem)) {
set_bit(JOB_PROMISC, &ai->jobs);
wake_up_interruptible(&ai->thr_wait);
} else
@@ -3213,7 +3213,7 @@ static irqreturn_t airo_interrupt(int irq, void *dev_id)
set_bit(FLAG_UPDATE_UNI, &apriv->flags);
set_bit(FLAG_UPDATE_MULTI, &apriv->flags);

- if (down_trylock(&apriv->sem) != 0) {
+ if (!down_try(&apriv->sem)) {
set_bit(JOB_EVENT, &apriv->jobs);
wake_up_interruptible(&apriv->thr_wait);
} else
@@ -7659,7 +7659,7 @@ static struct iw_statistics *airo_get_wireless_stats(struct net_device *dev)

if (!test_bit(JOB_WSTATS, &local->jobs)) {
/* Get stats out of the card if available */
- if (down_trylock(&local->sem) != 0) {
+ if (!down_try(&local->sem)) {
set_bit(JOB_WSTATS, &local->jobs);
wake_up_interruptible(&local->thr_wait);
} else
diff --git a/drivers/scsi/aacraid/commsup.c b/drivers/scsi/aacraid/commsup.c
index 289304a..c011d05 100644
--- a/drivers/scsi/aacraid/commsup.c
+++ b/drivers/scsi/aacraid/commsup.c
@@ -490,7 +490,7 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size,
* hardware failure has occurred.
*/
unsigned long count = 36000000L; /* 3 minutes */
- while (down_trylock(&fibptr->event_wait)) {
+ while (!down_try(&fibptr->event_wait)) {
int blink;
if (--count == 0) {
struct aac_queue * q = &dev->queues->queue[AdapNormCmdQueue];
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 84fcaa6..f31f0c5 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -477,7 +477,7 @@ int usb_lock_device_for_reset(struct usb_device *udev,
}
}

- while (usb_trylock_device(udev) != 0) {
+ while (!usb_trylock_device(udev)) {

/* If we can't acquire the lock after waiting one second,
* we're probably deadlocked */
diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index f4585d3..981275b 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -297,7 +297,7 @@ get_ready_ep (unsigned f_flags, struct ep_data *epdata)
int val;

if (f_flags & O_NONBLOCK) {
- if (down_trylock (&epdata->lock) != 0)
+ if (!down_try (&epdata->lock))
goto nonblock;
if (epdata->state != STATE_EP_ENABLED) {
up (&epdata->lock);
diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c
index 2eb48c0..5c43dd5 100644
--- a/drivers/watchdog/ar7_wdt.c
+++ b/drivers/watchdog/ar7_wdt.c
@@ -179,7 +179,7 @@ static void ar7_wdt_disable_wdt(void)
static int ar7_wdt_open(struct inode *inode, struct file *file)
{
/* only allow one at a time */
- if (down_trylock(&open_semaphore))
+ if (!down_try(&open_semaphore))
return -EBUSY;
ar7_wdt_enable_wdt();
expect_close = 0;
diff --git a/drivers/watchdog/it8712f_wdt.c b/drivers/watchdog/it8712f_wdt.c
index 445b7e8..c9a057c 100644
--- a/drivers/watchdog/it8712f_wdt.c
+++ b/drivers/watchdog/it8712f_wdt.c
@@ -306,7 +306,7 @@ static int
it8712f_wdt_open(struct inode *inode, struct file *file)
{
/* only allow one at a time */
- if (down_trylock(&it8712f_wdt_sem))
+ if (!down_try(&it8712f_wdt_sem))
return -EBUSY;
it8712f_wdt_enable();

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 98532c0..23f470a 100644
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -211,7 +211,7 @@ static int s3c2410wdt_set_heartbeat(int timeout)

static int s3c2410wdt_open(struct inode *inode, struct file *file)
{
- if(down_trylock(&open_lock))
+ if(!down_try(&open_lock))
return -EBUSY;

if (nowayout)
diff --git a/drivers/watchdog/sc1200wdt.c b/drivers/watchdog/sc1200wdt.c
index 35cddff..c080e6a 100644
--- a/drivers/watchdog/sc1200wdt.c
+++ b/drivers/watchdog/sc1200wdt.c
@@ -151,7 +151,7 @@ static inline int sc1200wdt_status(void)
static int sc1200wdt_open(struct inode *inode, struct file *file)
{
/* allow one at a time */
- if (down_trylock(&open_sem))
+ if (!down_try(&open_sem))
return -EBUSY;

if (timeout > MAX_TIMEOUT)
diff --git a/drivers/watchdog/scx200_wdt.c b/drivers/watchdog/scx200_wdt.c
index d55882b..e131988 100644
--- a/drivers/watchdog/scx200_wdt.c
+++ b/drivers/watchdog/scx200_wdt.c
@@ -92,7 +92,7 @@ static void scx200_wdt_disable(void)
static int scx200_wdt_open(struct inode *inode, struct file *file)
{
/* only allow one at a time */
- if (down_trylock(&open_semaphore))
+ if (!down_try(&open_semaphore))
return -EBUSY;
scx200_wdt_enable();

diff --git a/drivers/watchdog/wdt_pci.c b/drivers/watchdog/wdt_pci.c
index 1355608..c20690d 100644
--- a/drivers/watchdog/wdt_pci.c
+++ b/drivers/watchdog/wdt_pci.c
@@ -426,7 +426,7 @@ static int wdtpci_ioctl(struct inode *inode, struct file *file, unsigned int cmd

static int wdtpci_open(struct inode *inode, struct file *file)
{
- if (down_trylock(&open_sem))
+ if (!down_try(&open_sem))
return -EBUSY;

if (nowayout) {
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 7e9e4c7..64211fc 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1062,10 +1062,6 @@ void ocfs2_clear_inode(struct inode *inode)
(unsigned long long)oi->ip_blkno);
mutex_unlock(&oi->ip_io_mutex);

- /*
- * down_trylock() returns 0, down_write_trylock() returns 1
- * kernel 1, world 0
- */
mlog_bug_on_msg(!down_write_trylock(&oi->ip_alloc_sem),
"Clear inode of %llu, alloc_sem is locked\n",
(unsigned long long)oi->ip_blkno);
diff --git a/fs/xfs/linux-2.6/sema.h b/fs/xfs/linux-2.6/sema.h
index 3abe7e9..7d20f04 100644
--- a/fs/xfs/linux-2.6/sema.h
+++ b/fs/xfs/linux-2.6/sema.h
@@ -36,17 +36,15 @@ typedef struct semaphore sema_t;

static inline int issemalocked(sema_t *sp)
{
- return down_trylock(sp) || (up(sp), 0);
+ return !down_try(sp) || (up(sp), 0);
}

/*
- * Map cpsema (try to get the sema) to down_trylock. We need to switch
- * the return values since cpsema returns 1 (acquired) 0 (failed) and
- * down_trylock returns the reverse 0 (acquired) 1 (failed).
+ * Map cpsema (try to get the sema) to down_try.
*/
static inline int cpsema(sema_t *sp)
{
- return down_trylock(sp) ? 0 : 1;
+ return down_try(sp);
}

#endif /* __XFS_SUPPORT_SEMA_H__ */
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 9cc8f02..09e50cd 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -538,7 +538,7 @@ found:
* if this does not work then we need to drop the
* spinlock and do a hard attempt on the semaphore.
*/
- if (down_trylock(&bp->b_sema)) {
+ if (!down_try(&bp->b_sema)) {
if (!(flags & XBF_TRYLOCK)) {
/* wait for buffer ownership */
XB_TRACE(bp, "get_lock", 0);
@@ -882,7 +882,7 @@ xfs_buf_cond_lock(
{
int locked;

- locked = down_trylock(&bp->b_sema) == 0;
+ locked = down_try(&bp->b_sema);
if (locked) {
XB_SET_OWNER(bp);
}
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index bc6da10..c1f5b3f 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -141,10 +141,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock);
# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
#endif

-/*
- * NOTE: mutex_trylock() follows the spin_trylock() convention,
- * not the down_trylock() convention!
- */
extern int mutex_trylock(struct mutex *lock);
extern void mutex_unlock(struct mutex *lock);

diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h
index 7415839..00af3c2 100644
--- a/include/linux/semaphore.h
+++ b/include/linux/semaphore.h
@@ -42,8 +42,12 @@ static inline void sema_init(struct semaphore *sem, int val)
extern void down(struct semaphore *sem);
extern int __must_check down_interruptible(struct semaphore *sem);
extern int __must_check down_killable(struct semaphore *sem);
-extern int __must_check down_trylock(struct semaphore *sem);
+extern bool __must_check down_try(struct semaphore *sem);
+/* Old down_trylock() returned the opposite of what was expected. */
+static inline int __deprecated down_trylock(struct semaphore *sem)
+{
+ return !down_try(sem);
+}
extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
extern void up(struct semaphore *sem);
-
#endif /* __LINUX_SEMAPHORE_H */
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 5811c5d..2664efd 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -492,7 +492,7 @@ extern void usb_put_dev(struct usb_device *dev);
/* USB device locking */
#define usb_lock_device(udev) down(&(udev)->dev.sem)
#define usb_unlock_device(udev) up(&(udev)->dev.sem)
-#define usb_trylock_device(udev) down_trylock(&(udev)->dev.sem)
+#define usb_trylock_device(udev) down_try(&(udev)->dev.sem)
extern int usb_lock_device_for_reset(struct usb_device *udev,
const struct usb_interface *iface);

diff --git a/kernel/mutex.c b/kernel/mutex.c
index 12c779d..38823ca 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -371,8 +371,8 @@ static inline int __mutex_trylock_slowpath(atomic_t *lock_count)
* Try to acquire the mutex atomically. Returns 1 if the mutex
* has been acquired successfully, and 0 on contention.
*
- * NOTE: this function follows the spin_trylock() convention, so
- * it is negated to the down_trylock() return values! Be careful
+ * NOTE: this function follows the spin_trylock()/down_try() convention,
+ * so it is negated to the old down_trylock() return values! Be careful
* about this when converting semaphore users to mutexes.
*
* This function must not be used in interrupt context. The
diff --git a/kernel/printk.c b/kernel/printk.c
index b51b156..ab30884 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -969,7 +969,7 @@ EXPORT_SYMBOL(acquire_console_sem);

int try_acquire_console_sem(void)
{
- if (down_trylock(&console_sem))
+ if (!down_try(&console_sem))
return -1;
console_locked = 1;
console_may_schedule = 0;
@@ -1068,7 +1068,7 @@ void console_unblank(void)
* oops_in_progress is set to 1..
*/
if (oops_in_progress) {
- if (down_trylock(&console_sem) != 0)
+ if (!down_try(&console_sem))
return;
} else
acquire_console_sem();
diff --git a/kernel/semaphore.c b/kernel/semaphore.c
index aaaeae8..e9fdc4e 100644
--- a/kernel/semaphore.c
+++ b/kernel/semaphore.c
@@ -14,7 +14,7 @@
* Some notes on the implementation:
*
* The spinlock controls access to the other members of the semaphore.
- * down_trylock() and up() can be called from interrupt context, so we
+ * down_try() and up() can be called from interrupt context, so we
* have to disable interrupts when taking the lock. It turns out various
* parts of the kernel expect to be able to use down() on a semaphore in
* interrupt context when they know it will succeed, so we have to use
@@ -115,19 +115,18 @@ int down_killable(struct semaphore *sem)
EXPORT_SYMBOL(down_killable);

/**
- * down_trylock - try to acquire the semaphore, without waiting
+ * down_try - try to acquire the semaphore, without waiting
* @sem: the semaphore to be acquired
*
- * Try to acquire the semaphore atomically. Returns 0 if the mutex has
- * been acquired successfully or 1 if it it cannot be acquired.
+ * Try to acquire the semaphore atomically. Returns true if the mutex has
+ * been acquired successfully or 0 if it it cannot be acquired.
*
- * NOTE: This return value is inverted from both spin_trylock and
- * mutex_trylock! Be careful about this when converting code.
+ * NOTE: This replaces down_trylock() which returned the reverse.
*
* Unlike mutex_trylock, this function can be used from interrupt context,
* and the semaphore can be released by any task or interrupt.
*/
-int down_trylock(struct semaphore *sem)
+bool down_try(struct semaphore *sem)
{
unsigned long flags;
int count;
@@ -138,9 +137,9 @@ int down_trylock(struct semaphore *sem)
sem->count = count;
spin_unlock_irqrestore(&sem->lock, flags);

- return (count < 0);
+ return (count >= 0);
}
-EXPORT_SYMBOL(down_trylock);
+EXPORT_SYMBOL(down_try);

/**
* down_timeout - acquire the semaphore within a specified time

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