mirror of
https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
bpf: cpumap fix potential lost wake-up problem
As pointed out by Michael, commit1c601d829a
("bpf: cpumap xdp_buff to skb conversion and allocation") contains a classical example of the potential lost wake-up problem. We need to recheck the condition __ptr_ring_empty() after changing current->state to TASK_INTERRUPTIBLE, this avoids a race between wake_up_process() and schedule(). After this, a race with wake_up_process() will simply change the state to TASK_RUNNING, and the schedule() call not really put us to sleep. Fixes:1c601d829a
("bpf: cpumap xdp_buff to skb conversion and allocation") Reported-by: "Michael S. Tsirkin" <mst@redhat.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
7f6b437e9b
commit
31749468c3
|
@ -288,13 +288,17 @@ static int cpu_map_kthread_run(void *data)
|
|||
|
||||
/* Release CPU reschedule checks */
|
||||
if (__ptr_ring_empty(rcpu->queue)) {
|
||||
__set_current_state(TASK_INTERRUPTIBLE);
|
||||
schedule();
|
||||
sched = 1;
|
||||
set_current_state(TASK_INTERRUPTIBLE);
|
||||
/* Recheck to avoid lost wake-up */
|
||||
if (__ptr_ring_empty(rcpu->queue)) {
|
||||
schedule();
|
||||
sched = 1;
|
||||
} else {
|
||||
__set_current_state(TASK_RUNNING);
|
||||
}
|
||||
} else {
|
||||
sched = cond_resched();
|
||||
}
|
||||
__set_current_state(TASK_RUNNING);
|
||||
|
||||
/* Process packets in rcpu->queue */
|
||||
local_bh_disable();
|
||||
|
|
Loading…
Reference in a new issue