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autofs4: autofs4_wait() vs. autofs4_catatonic_mode() race

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We need to recheck ->catatonic after autofs4_wait() got ->wq_mutex
for good, or we might end up with wq inserted into queue after
autofs4_catatonic_mode() had done its thing.  It will stick there
forever, since there won't be anything to clear its ->name.name.

A bit of a complication: validate_request() drops and regains ->wq_mutex.
It actually ends up the most convenient place to stick the check into...

Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-01-10 22:20:12 -05:00
parent b3f2a92447
commit 4041bcdc7b
1 changed files with 7 additions and 1 deletions
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8
fs/autofs4/waitq.c
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@ -257,6 +257,9 @@ static int validate_request(struct autofs_wait_queue **wait,
struct autofs_wait_queue *wq;
struct autofs_info *ino;
if (sbi->catatonic)
return -ENOENT;
/* Wait in progress, continue; */
wq = autofs4_find_wait(sbi, qstr);
if (wq) {
@ -289,6 +292,9 @@ static int validate_request(struct autofs_wait_queue **wait,
if (mutex_lock_interruptible(&sbi->wq_mutex))
return -EINTR;
if (sbi->catatonic)
return -ENOENT;
wq = autofs4_find_wait(sbi, qstr);
if (wq) {
*wait = wq;
@ -389,7 +395,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
ret = validate_request(&wq, sbi, &qstr, dentry, notify);
if (ret <= 0) {
if (ret == 0)
if (ret != -EINTR)
mutex_unlock(&sbi->wq_mutex);
kfree(qstr.name);
return ret;