[lustre-devel] [PATCH 23/34] lnet: don't need lock to test ln_shutdown.

[Doug Oucharek]

It seems the selection code being affected by this patch later gets moved to its own routine called lnet_select_pathway().  The logic is completely re-written so it may not be important to fix the use of locks here.  However,  it is not good that the lock is not being held while checking for shutdown.

Reviewed-by: Doug Oucharek <dougso at me.com>

Doug

On 9/6/18, 5:54 PM, "NeilBrown" <neilb at suse.com> wrote:

    ln_shutdown returns -ESHUTDOWN if ln_shutdown
    is already set.
    The lock is always taken to set ln_shutdown, but apparently
    we don't need to hold the lock for this test.
    I guess if it is set immediately after the test, and before
    we take the lock then.... can anything bad happen?
    
    This is part of
        8cbb8cd3e771e7f7e0f99cafc19fad32770dc015
           LU-7734 lnet: Multi-Rail local NI split
    
    Signed-off-by: NeilBrown <neilb at suse.com>
    ---
     drivers/staging/lustre/lnet/lnet/lib-move.c |    7 ++-----
     1 file changed, 2 insertions(+), 5 deletions(-)
    
    diff --git a/drivers/staging/lustre/lnet/lnet/lib-move.c b/drivers/staging/lustre/lnet/lnet/lib-move.c
    index 60f34c4b85d3..46e593fbb44f 100644
    --- a/drivers/staging/lustre/lnet/lnet/lib-move.c
    +++ b/drivers/staging/lustre/lnet/lnet/lib-move.c
    @@ -1099,12 +1099,9 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     	cpt = lnet_cpt_of_nid(rtr_nid == LNET_NID_ANY ? dst_nid : rtr_nid,
     			      local_ni);
      again:
    -	lnet_net_lock(cpt);
    -
    -	if (the_lnet.ln_shutdown) {
    -		lnet_net_unlock(cpt);
    +	if (the_lnet.ln_shutdown)
     		return -ESHUTDOWN;
    -	}
    +	lnet_net_lock(cpt);
     
     	if (src_nid == LNET_NID_ANY) {
     		src_ni = NULL;