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authorMike Christie <mchristi@redhat.com>2017-03-02 04:59:50 -0600
committerNicholas Bellinger <nab@linux-iscsi.org>2017-03-18 14:47:29 -0700
commit760bf578edf8122f2503a3a6a3f4b0de3b6ce0bb (patch)
tree04ff648b353fc494e0b3eb6c209578d40fa0c742 /drivers/target
parent1ca4d4fa3bfcbe8964f81e5818a9b90436466eb0 (diff)
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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/target')
-rw-r--r--drivers/target/target_core_alua.c10
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