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authorWilly Tarreau <w@1wt.eu>2017-09-07 11:56:40 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-18 11:11:07 +0100
commite8d650563c5fc1ef9f862a8122397e18043fd51b (patch)
treedc83c8f8fb1d605255c918d7ab6ee30f72056567
parent01000c56caccf36ddd253bb15036a1cbb93ad27f (diff)
misc: panel: properly restore atomic counter on error path
commit 93dc1774d2a4c7a298d5cdf78cc8acdcb7b1428d upstream. Commit f4757af ("staging: panel: Fix single-open policy race condition") introduced in 3.19-rc1 attempted to fix a race condition on the open, but failed to properly do it and used to exit without restoring the semaphore. This results in -EBUSY being returned after the first open error until the module is reloaded or the system restarted (ie: consecutive to a dual open resulting in -EBUSY or to a permission error). Fixes: f4757af85 # 3.19-rc1 Cc: Mariusz Gorski <marius.gorski@gmail.com> Signed-off-by: Willy Tarreau <w@1wt.eu> [wt: driver is in staging/panel in 4.4] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/staging/panel/panel.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
index 70b8f4fabfad..e658e11e1829 100644
--- a/drivers/staging/panel/panel.c
+++ b/drivers/staging/panel/panel.c
@@ -1431,17 +1431,25 @@ static ssize_t lcd_write(struct file *file,
static int lcd_open(struct inode *inode, struct file *file)
{
+ int ret;
+
+ ret = -EBUSY;
if (!atomic_dec_and_test(&lcd_available))
- return -EBUSY; /* open only once at a time */
+ goto fail; /* open only once at a time */
+ ret = -EPERM;
if (file->f_mode & FMODE_READ) /* device is write-only */
- return -EPERM;
+ goto fail;
if (lcd.must_clear) {
lcd_clear_display();
lcd.must_clear = false;
}
return nonseekable_open(inode, file);
+
+ fail:
+ atomic_inc(&lcd_available);
+ return ret;
}
static int lcd_release(struct inode *inode, struct file *file)
@@ -1704,14 +1712,21 @@ static ssize_t keypad_read(struct file *file,
static int keypad_open(struct inode *inode, struct file *file)
{
+ int ret;
+
+ ret = -EBUSY;
if (!atomic_dec_and_test(&keypad_available))
- return -EBUSY; /* open only once at a time */
+ goto fail; /* open only once at a time */
+ ret = -EPERM;
if (file->f_mode & FMODE_WRITE) /* device is read-only */
- return -EPERM;
+ goto fail;
keypad_buflen = 0; /* flush the buffer on opening */
return 0;
+ fail:
+ atomic_inc(&keypad_available);
+ return ret;
}
static int keypad_release(struct inode *inode, struct file *file)