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c1481c94e7
Blamed commit introduced a busy-wait loop in tipc_exit_net()
to wait for pending UDP bearer cleanup works to complete:
while (atomic_read(&tn->wq_count))
cond_resched();
This loop can busy-wait for a long time if cond_resched() is a NOP. This
typically happens if the netns exit is executed by a high priority task,
or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In
such cases, it wastes CPU cycles and can lead to soft lockups.
Fix this by replacing the busy loop with wait_var_event(), allowing the
thread to sleep properly until the work queue count reaches zero.
Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and
wake_up_var() to wake up the waiter when the count drops to zero.
This uses the global wait queue hash table, avoiding the need to bloat
struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test()
provides the necessary memory barrier to ensure the wakeup is not missed.
Fixes:
|
||
|---|---|---|
| .. | ||
| addr.c | ||
| addr.h | ||
| bcast.c | ||
| bcast.h | ||
| bearer.c | ||
| bearer.h | ||
| core.c | ||
| core.h | ||
| crypto.c | ||
| crypto.h | ||
| diag.c | ||
| discover.c | ||
| discover.h | ||
| eth_media.c | ||
| group.c | ||
| group.h | ||
| ib_media.c | ||
| Kconfig | ||
| link.c | ||
| link.h | ||
| Makefile | ||
| monitor.c | ||
| monitor.h | ||
| msg.c | ||
| msg.h | ||
| name_distr.c | ||
| name_distr.h | ||
| name_table.c | ||
| name_table.h | ||
| net.c | ||
| net.h | ||
| netlink_compat.c | ||
| netlink.c | ||
| netlink.h | ||
| node.c | ||
| node.h | ||
| socket.c | ||
| socket.h | ||
| subscr.c | ||
| subscr.h | ||
| sysctl.c | ||
| topsrv.c | ||
| topsrv.h | ||
| trace.c | ||
| trace.h | ||
| udp_media.c | ||
| udp_media.h | ||