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Subject[PATCH 14/16] isdn: divert, hysdn: fix interruptible_sleep_on race
Date
These two drivers use identical code for their procfs status
file handling, which contains a small race against status
data becoming available while reading the file.

This uses wait_event_interruptible instead to fix this
particular race and eventually get rid of all sleep_on
instances. There seems to be another race involving
multiple concurrent readers of the same procfs file, which
I don't try to fix here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
---
drivers/isdn/divert/divert_procfs.c | 7 ++++---
drivers/isdn/hysdn/hysdn_proclog.c | 7 ++++---
2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/isdn/divert/divert_procfs.c b/drivers/isdn/divert/divert_procfs.c
index fb4f1ba..1c5dc34 100644
--- a/drivers/isdn/divert/divert_procfs.c
+++ b/drivers/isdn/divert/divert_procfs.c
@@ -86,12 +86,13 @@ isdn_divert_read(struct file *file, char __user *buf, size_t count, loff_t *off)
struct divert_info *inf;
int len;

- if (!*((struct divert_info **) file->private_data)) {
+ if (!(inf = *((struct divert_info **) file->private_data))) {
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
- interruptible_sleep_on(&(rd_queue));
+ wait_event_interruptible(rd_queue, (inf =
+ *((struct divert_info **) file->private_data)));
}
- if (!(inf = *((struct divert_info **) file->private_data)))
+ if (!inf)
return (0);

inf->usage_cnt--; /* new usage count */
diff --git a/drivers/isdn/hysdn/hysdn_proclog.c b/drivers/isdn/hysdn/hysdn_proclog.c
index b61e8d5..7b5fd8f 100644
--- a/drivers/isdn/hysdn/hysdn_proclog.c
+++ b/drivers/isdn/hysdn/hysdn_proclog.c
@@ -175,14 +175,15 @@ hysdn_log_read(struct file *file, char __user *buf, size_t count, loff_t *off)
int len;
hysdn_card *card = PDE_DATA(file_inode(file));

- if (!*((struct log_data **) file->private_data)) {
+ if (!(inf = *((struct log_data **) file->private_data))) {
struct procdata *pd = card->proclog;
if (file->f_flags & O_NONBLOCK)
return (-EAGAIN);

- interruptible_sleep_on(&(pd->rd_queue));
+ wait_event_interruptible(pd->rd_queue, (inf =
+ *((struct log_data **) file->private_data)));
}
- if (!(inf = *((struct log_data **) file->private_data)))
+ if (!inf)
return (0);

inf->usage_cnt--; /* new usage count */
--
1.8.3.2


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