diff options
| author |   Linus Torvalds <torvalds@linux-foundation.org> | 2018-03-14 16:51:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-03-14 16:51:33 -0700 |
| commit | fed8f5090ca647b7cf37c21f92053e517526133a (patch) | |
| tree | 4cd2a81f2aa42c7636b263f02560b1b7b1af49f4 /drivers | |
| parent | Revert "mm/page_alloc: fix memmap_init_zone pageblock alignment" (diff) | |
| parent | RDMAVT: Fix synchronization around percpu_ref (diff) | |
| download | linux-dev-fed8f5090ca647b7cf37c21f92053e517526133a.tar.xz linux-dev-fed8f5090ca647b7cf37c21f92053e517526133a.zip | |
Merge branch 'percpu_ref-rcu-audit-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc
Pull percpu_ref rcu fixes from Tejun Heo:
"Jann Horn found that aio was depending on the internal RCU grace
periods of percpu-ref and that it's broken because aio uses regular
RCU while percpu_ref uses sched-RCU.
Depending on percpu_ref's internal grace periods isn't a good idea
because
- The RCU type might not match.
- percpu_ref's grace periods are used to switch to atomic mode. They
aren't between the last put and the invocation of the last release.
This is easy to get confused about and can lead to subtle bugs.
- percpu_ref might not have grace periods at all depending on its
current operation mode.
This patchset audits and fixes percpu_ref users for their RCU usages"
[ There's a continuation of this series that clarifies percpu_ref
documentation that the internal grace periods must not be depended
upon, and introduces rcu_work to simplify bouncing to a workqueue
after an RCU grace period.
That will go in for 4.17 - this is just the minimal set with the fixes
that are tagged for -stable ]
* 'percpu_ref-rcu-audit-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc:
RDMAVT: Fix synchronization around percpu_ref
fs/aio: Use RCU accessors for kioctx_table->table[]
fs/aio: Add explicit RCU grace period when freeing kioctx
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/infiniband/sw/rdmavt/mr.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/infiniband/sw/rdmavt/mr.c b/drivers/infiniband/sw/rdmavt/mr.c index 1b2e5362a3ff..cc429b567d0a 100644 --- a/drivers/infiniband/sw/rdmavt/mr.c +++ b/drivers/infiniband/sw/rdmavt/mr.c @@ -489,11 +489,13 @@ static int rvt_check_refs(struct rvt_mregion *mr, const char *t) unsigned long timeout; struct rvt_dev_info *rdi = ib_to_rvt(mr->pd->device); - if (percpu_ref_is_zero(&mr->refcount)) - return 0; - /* avoid dma mr */ - if (mr->lkey) + if (mr->lkey) { + /* avoid dma mr */ rvt_dereg_clean_qps(mr); + /* @mr was indexed on rcu protected @lkey_table */ + synchronize_rcu(); + } + timeout = wait_for_completion_timeout(&mr->comp, 5 * HZ); if (!timeout) { rvt_pr_err(rdi, |