On 13/04/2022 06.56, [EXT] 王斌 wrote:

Hi：

See lock_hash in h_table.c:

Flowing lines of code do not guarantee atomicity and I think it is not safe:

-atomic_get(&_tm_table->entries[i].locker_pid) != mypid

-lock(&_tm_table->entries[i].mutex)

-atomic_set(&_tm_table->entries[i].locker_pid, mypid)

Not my code, but I would say it is safe, because the only race condition you could possibly encounter where it would make a difference is when atomic_get(&locker_pid) returns a value other than mypid (true condition) and is then subsequently set to mypid by a different thread before the mutex can be acquired (flipping the condition to false), which cannot happen because all threads have different PIDs.

Cheers