diff options
| author | Mike Christie <mchristi@redhat.com> | 2017-03-02 04:59:50 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-20 10:04:57 +0100 |
| commit | c9b79738c0ab9c54d95760403cfd17f67f956a45 (patch) | |
| tree | 896d3d26fb84d9e234e2781a37f9efd42158e70a /drivers/target | |
| parent | dfd6deed831348fc8d6cb3efca1c68c3d5b195c7 (diff) | |
target: fix race during implicit transition work flushes
[ Upstream commit 760bf578edf8122f2503a3a6a3f4b0de3b6ce0bb ]
This fixes the following races:
1. core_alua_do_transition_tg_pt could have read
tg_pt_gp_alua_access_state and gone into this if chunk:
if (!explicit &&
atomic_read(&tg_pt_gp->tg_pt_gp_alua_access_state) ==
ALUA_ACCESS_STATE_TRANSITION) {
and then core_alua_do_transition_tg_pt_work could update the
state. core_alua_do_transition_tg_pt would then only set
tg_pt_gp_alua_pending_state and the tg_pt_gp_alua_access_state would
not get updated with the second calls state.
2. core_alua_do_transition_tg_pt could be setting
tg_pt_gp_transition_complete while the tg_pt_gp_transition_work
is already completing. core_alua_do_transition_tg_pt then waits on the
completion that will never be called.
To handle these issues, we just call flush_work which will return when
core_alua_do_transition_tg_pt_work has completed so there is no need
to do the complete/wait. And, if core_alua_do_transition_tg_pt_work
was running, instead of trying to sneak in the state change, we just
schedule up another core_alua_do_transition_tg_pt_work call.
Note that this does not handle a possible race where there are multiple
threads call core_alua_do_transition_tg_pt at the same time. I think
we need a mutex in target_tg_pt_gp_alua_access_state_store.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/target')
| -rw-r--r-- | drivers/target/target_core_alua.c | 10 |
1 files changed, 1 insertions, 9 deletions
diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c index 8eec0162acb1..1fe782f9ee81 100644 --- a/drivers/target/target_core_alua.c +++ b/drivers/target/target_core_alua.c @@ -1073,16 +1073,8 @@ static int core_alua_do_transition_tg_pt( /* * Flush any pending transitions */ - if (!explicit && atomic_read(&tg_pt_gp->tg_pt_gp_alua_access_state) == - ALUA_ACCESS_STATE_TRANSITION) { - /* Just in case */ - tg_pt_gp->tg_pt_gp_alua_pending_state = new_state; - tg_pt_gp->tg_pt_gp_transition_complete = &wait; + if (!explicit) flush_work(&tg_pt_gp->tg_pt_gp_transition_work); - wait_for_completion(&wait); - tg_pt_gp->tg_pt_gp_transition_complete = NULL; - return 0; - } /* * Save the old primary ALUA access state, and set the current state |