diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2021-03-11 11:26:00 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-17 16:07:19 +0100 |
| commit | 96f3135d3e5d3921c8b6eb9bf0f841ec4457f8b5 (patch) | |
| tree | db21438ab89ebac77f91bdbf79f93cccc6880a52 /kernel | |
| parent | 6fb7304f4526736417c48af821a85d1b94d634dd (diff) | |
futex: fix dead code in attach_to_pi_owner()
This patch comes directly from an origin patch (commit
91509e84949fc97e7424521c32a9e227746e0b85) in v4.9.
And it is part of a full patch which was originally back-ported
to v4.14 as commit e6e00df182908f34360c3c9f2d13cc719362e9c0
The handle_exit_race() function is defined in commit 9c3f39860367
("futex: Cure exit race"), which never returns -EBUSY. This results
in a small piece of dead code in the attach_to_pi_owner() function:
int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */
...
if (ret == -EBUSY)
*exiting = p; /* dead code */
The return value -EBUSY is added to handle_exit_race() in upsteam
commit ac31c7ff8624409 ("futex: Provide distinct return value when
owner is exiting"). This commit was incorporated into v4.9.255, before
the function handle_exit_race() was introduced, whitout Modify
handle_exit_race().
To fix dead code, extract the change of handle_exit_race() from
commit ac31c7ff8624409 ("futex: Provide distinct return value when owner
is exiting"), re-incorporated.
Lee writes:
This commit takes the remaining functional snippet of:
ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting")
... and is the correct fix for this issue.
Fixes: 9c3f39860367 ("futex: Cure exit race")
Cc: stable@vger.kernel.org # v4.9.258
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Reviewed-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/futex.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 4894c0934205..ff5499b0c5b3 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1204,11 +1204,11 @@ static int handle_exit_race(u32 __user *uaddr, u32 uval, u32 uval2; /* - * If the futex exit state is not yet FUTEX_STATE_DEAD, wait - * for it to finish. + * If the futex exit state is not yet FUTEX_STATE_DEAD, tell the + * caller that the alleged owner is busy. */ if (tsk && tsk->futex_state != FUTEX_STATE_DEAD) - return -EAGAIN; + return -EBUSY; /* * Reread the user space value to handle the following situation: |