Re: [PATCH, RFC 21/30] isdn: divert, hysdn: fix interruptible_sleep_on race
From: Sergei Shtylyov <hidden>
Date: 2014-01-02 15:01:18
Also in:
lkml
Hello. On 02-01-2014 16:07, Arnd Bergmann wrote:
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 <redacted> 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(-)
quoted hunk ↗ jump to hunk
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))) {
checkpatch.pl shouldn't approve assignment inside *if*. Though you're
moving it from the existing code, it wouldn't hurt to fix it.
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)));
Parens around assignment are hardly useful.
quoted hunk ↗ jump to hunk
} - 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))) {
Here too checkpatch.pk should complain...
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)));
And parens hardly needed.
WBR, Sergei