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Subject[PATCH 1/1] Media: radio: si470x: remove double mutex lock
Date
From: Alexander Strakh <cromlehg@gmail.com>


1. First mutex_lock on &radio->lock in line 441
2. Second in line 462

I think that mutex in line 462 is not needed. In kernel v2.6.36.3 function si470
x_rds_on contains mutex_lock/mutex_unlock. Have no mutex_lock in line 441. In kernel v2.6.37 mutex_lock/mutex_unlock has been moved from si470x_rds_on to fops_read. But old mutex_lock (line 462) forgot to remove.

433static ssize_t si470x_fops_read(struct file *file, char __user *buf,
434 size_t count, loff_t *ppos)
435{
....
441 mutex_lock(&radio->lock);
442 if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
443 si470x_rds_on(radio);
444
445 /* block if no new data available */
446 while (radio->wr_index == radio->rd_index) {
447 if (file->f_flags & O_NONBLOCK) {
448 retval = -EWOULDBLOCK;
449 goto done;
450 }
451 if (wait_event_interruptible(radio->read_queue,
452 radio->wr_index != radio->rd_index) < 0) {
453 retval = -EINTR;
454 goto done;
455 }
456 }
457
458 /* calculate block count from byte count */
459 count /= 3;
460
461 /* copy RDS block out of internal buffer and to user buffer */
462 mutex_lock(&radio->lock);

Found by Linux Device Drivers Verification Project

Remove second mutex_lock from fops_read

Signed-off-by: Alexander Strakh <strakh@ispras.ru>
---
drivers/media/radio/si470x/radio-si470x-common.c | 1 -
1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/drivers/media/radio/si470x/radio-si470x-common.c b/drivers/media/radio/si470x/radio-si470x-common.c
index 60c176f..38ae6cd 100644
--- a/drivers/media/radio/si470x/radio-si470x-common.c
+++ b/drivers/media/radio/si470x/radio-si470x-common.c
@@ -460,7 +460,6 @@ static ssize_t si470x_fops_read(struct file *file, char __user *buf,
count /= 3;

/* copy RDS block out of internal buffer and to user buffer */
- mutex_lock(&radio->lock);
while (block_count < count) {
if (radio->rd_index == radio->wr_index)
break;
--
1.7.1


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