FEX-Emu/linux
1
0
Fork 0
mirror of https://github.com/FEX-Emu/linux.git synced 2024-12-16 22:10:24 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

IB/fmr: ib_flush_fmr_pool() may wait too long

Browse Source 
ib_flush_fmr_pool() stashes away the request generation number
properly, but then goes ahead and rereads it every time it tests
whether the flush generation number has caught up.  This means that
there is a theoretical possibility of livelock, if the request
generation number keeps getting bumped and the flush generation number
never catches up.  The fix is simple: use the request generation
number read at the beginning of the function.

Also, atomic_inc() followed by atomic_read() can be replaced with
atomic_int_return().  There's no real requirement for atomicity here
but we might as well shrink the code.

This bug was discovered using David Binderman's list of "set but never
used" warnings from icc.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Roland Dreier 2006-12-12 11:50:19 -08:00
parent e1036502e5
commit f47e22c6e4
1 changed files with 2 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/infiniband/core/fmr_pool.c
View File

@ -394,20 +394,12 @@ EXPORT_SYMBOL(ib_destroy_fmr_pool);
*/
int ib_flush_fmr_pool(struct ib_fmr_pool *pool)
{
int serial;
atomic_inc(&pool->req_ser);
/*
* It's OK if someone else bumps req_ser again here -- we'll
* just wait a little longer.
*/
serial = atomic_read(&pool->req_ser);
int serial = atomic_inc_return(&pool->req_ser);
wake_up_process(pool->thread);
if (wait_event_interruptible(pool->force_wait,
atomic_read(&pool->flush_ser) -
atomic_read(&pool->req_ser) >= 0))
atomic_read(&pool->flush_ser) - serial >= 0))
return -EINTR;
return 0;