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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 11:22:25 +0100
commite81b96cab11f57506ade92656a76db8bbe7b6673 (patch)
tree7e2411f0a8f8b2f0d4c37241b3453041f81cf860
parentb2dbcb7c969dcb6a2dcbe901a4a9070bb30e4788 (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 misc/panel in 4.9] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/misc/panel.c23
1 files changed, 19 insertions, 4 deletions
diff --git a/drivers/misc/panel.c b/drivers/misc/panel.c
index 6030ac5b8c63..a9fa4c0ac220 100644
--- a/drivers/misc/panel.c
+++ b/drivers/misc/panel.c
@@ -1423,17 +1423,25 @@ 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)
@@ -1696,14 +1704,21 @@ 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)