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| author | Anton Volkov <avolkov@ispras.ru> | 2017-08-07 15:54:14 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-07 11:25:14 -0700 |
| commit | b925ef37b0a152b0c06aa43bc9204d0116f676d7 (patch) | |
| tree | ae634920cf42835cad86baddf89b06be3662510a /drivers/isdn | |
| parent | ec2c6726322f0d270bab477e4904bf9496f70ee5 (diff) | |
| download | linux-stable-b925ef37b0a152b0c06aa43bc9204d0116f676d7.tar.gz linux-stable-b925ef37b0a152b0c06aa43bc9204d0116f676d7.tar.bz2 linux-stable-b925ef37b0a152b0c06aa43bc9204d0116f676d7.zip | |
hysdn: fix to a race condition in put_log_buffer
The synchronization type that was used earlier to guard the loop that
deletes unused log buffers may lead to a situation that prevents any
thread from going through the loop.
The patch deletes previously used synchronization mechanism and moves
the loop under the spin_lock so the similar cases won't be feasible in
the future.
Found by by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Anton Volkov <avolkov@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/isdn')
| -rw-r--r-- | drivers/isdn/hysdn/hysdn_proclog.c | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/drivers/isdn/hysdn/hysdn_proclog.c b/drivers/isdn/hysdn/hysdn_proclog.c index 7b5fd8fb1761..aaca0b3d662e 100644 --- a/drivers/isdn/hysdn/hysdn_proclog.c +++ b/drivers/isdn/hysdn/hysdn_proclog.c @@ -44,7 +44,6 @@ struct procdata { char log_name[15]; /* log filename */ struct log_data *log_head, *log_tail; /* head and tail for queue */ int if_used; /* open count for interface */ - int volatile del_lock; /* lock for delete operations */ unsigned char logtmp[LOG_MAX_LINELEN]; wait_queue_head_t rd_queue; }; @@ -102,7 +101,6 @@ put_log_buffer(hysdn_card *card, char *cp) { struct log_data *ib; struct procdata *pd = card->proclog; - int i; unsigned long flags; if (!pd) @@ -126,21 +124,21 @@ put_log_buffer(hysdn_card *card, char *cp) else pd->log_tail->next = ib; /* follows existing messages */ pd->log_tail = ib; /* new tail */ - i = pd->del_lock++; /* get lock state */ - spin_unlock_irqrestore(&card->hysdn_lock, flags); /* delete old entrys */ - if (!i) - while (pd->log_head->next) { - if ((pd->log_head->usage_cnt <= 0) && - (pd->log_head->next->usage_cnt <= 0)) { - ib = pd->log_head; - pd->log_head = pd->log_head->next; - kfree(ib); - } else - break; - } /* pd->log_head->next */ - pd->del_lock--; /* release lock level */ + while (pd->log_head->next) { + if ((pd->log_head->usage_cnt <= 0) && + (pd->log_head->next->usage_cnt <= 0)) { + ib = pd->log_head; + pd->log_head = pd->log_head->next; + kfree(ib); + } else { + break; + } + } /* pd->log_head->next */ + + spin_unlock_irqrestore(&card->hysdn_lock, flags); + wake_up_interruptible(&(pd->rd_queue)); /* announce new entry */ } /* put_log_buffer */ |