Hi,
On Fri, Mar 1, 2024 at 11:25 AM Paulo Alcantara <pc@xxxxxxxxxxxxx> wrote:
>
> Hi Zorro,
>
> The problem is that cifs.ko is returning -EACCES from fcntl(2) called
> in do_test_equal_file_lock() but it is expecting -EAGAIN to be
> returned, so it hangs in wait4(2):
>
> ...
> [pid 14846] fcntl(3, F_SETLK, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=1}) = -1 EACCES (Permission denied)
> [pid 14846] wait4(-1,
>
> The man page says:
>
> F_SETLK (struct flock *)
> Acquire a lock (when l_type is F_RDLCK or F_WRLCK) or release a
> lock (when l_type is F_UNLCK) on the bytes specified by the
> l_whence, l_start, and l_len fields of lock. If a conflicting
> lock is held by another process, this call returns -1 and sets
> errno to EACCES or EAGAIN. (The error returned in this case
> differs across implementations, so POSIX requires a portable ap‐
> plication to check for both errors.)
>
> so fcntl_lock_corner_tests should also handle -EACCES.
>
yes, that is a bug in the test but in my opinion there is still an
issue. The mentioned fcntl(F_SETLK) above is just a sanity check to
print out if something is not correct and it will print out that
something is not correct and fails.
The problem is that wait() below, the child processes are not
returning and are in a blocking state which should not be the case.
What the test is doing is the following:
parent:
1. lock(A) # should be successful to acquire
child:
thread0:
2. lock(A) # should block
thread1:
3. lock(A) # should block
parent:
5. sleep(3) #wait until child are in blocking state of lock(A)
5. unlock(A) # both threads of the child should unlock and exit
...
6. sleep 3 # wait for pending unlock op (not really sure if it's necessary)
...
7. trylock(A) # mentioned sanity check
8. wait(NULL) # wait for child to exit
The unlock(A) should unblock the child threads, it is important to
mention that this test does a lock corner test and the lock(A) in both
threads ends in a ->lock() call with a "struct file_lock" that has
mostly the same fields. We had issues with that in gfs2 and a lookup
function to find the right request with an async complete handler of
the lock operation.
- Alex
