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| author |   Mike Christie <mchristi@redhat.com> | 2017-03-02 04:59:50 -0600 |
|---|---|---|
| committer |   Nicholas Bellinger <nab@linux-iscsi.org> | 2017-03-18 14:47:29 -0700 |
| commit | 760bf578edf8122f2503a3a6a3f4b0de3b6ce0bb (patch) | |
| tree | 04ff648b353fc494e0b3eb6c209578d40fa0c742 /drivers | |
| parent | target: allow userspace to set state to transitioning (diff) | |
| download | linux-dev-760bf578edf8122f2503a3a6a3f4b0de3b6ce0bb.tar.xz linux-dev-760bf578edf8122f2503a3a6a3f4b0de3b6ce0bb.zip | |
target: fix race during implicit transition work flushes
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>
Diffstat (limited to 'drivers')
| -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 252d4e4b7b33..fd7c16a7ca6e 100644 --- a/drivers/target/target_core_alua.c +++ b/drivers/target/target_core_alua.c @@ -1079,16 +1079,8 @@ 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 |