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| author |   Dmitry Bogdanov <d.bogdanov@yadro.com> | 2022-07-28 00:41:24 +0300 |
|---|---|---|
| committer |   Martin K. Petersen <martin.petersen@oracle.com> | 2022-08-01 19:36:02 -0400 |
| commit | dd0a66ada0bd0ae6c96ea45cfa1581797e867a40 (patch) | |
| tree | f492da5297b6a72127b5b46cfa171bc8ec936921 /drivers/target | |
| parent | scsi: ufs: core: Correct ufshcd_shutdown() flow (diff) | |
| download | linux-dev-dd0a66ada0bd0ae6c96ea45cfa1581797e867a40.tar.xz linux-dev-dd0a66ada0bd0ae6c96ea45cfa1581797e867a40.zip | |
scsi: target: core: Fix race during ACL removal
Under huge load there is a possibility of race condition in updating
se_dev_entry object in ACL removal procedure:
NIP [c0080000154093d0] transport_lookup_cmd_lun+0x1f8/0x3d0 [target_core_mod]
LR [c00800001542ab34] target_submit_cmd_map_sgls+0x11c/0x300 [target_core_mod]
Call Trace:
target_submit_cmd_map_sgls+0x11c/0x300 [target_core_mod]
target_submit_cmd+0x44/0x60 [target_core_mod]
tcm_qla2xxx_handle_cmd+0x88/0xe0 [tcm_qla2xxx]
qlt_do_work+0x2e4/0x3d0 [qla2xxx]
process_one_work+0x298/0x5c
Despite usage of RCU primitives with deve->se_lun pointer, it has not
become dereference-safe because deve->se_lun is updated and not
synchronized with a reader. That change might be in a release function
called by synchronize_rcu(). But, in fact, there is no point in setting
that pointer to NULL for deleting deve. All access to deve->se_lun is
already under rcu_read_lock. And either deve->se_lun is always valid or
deve is not valid itself and will not be found in the list_for_*. The same
applicable for deve->se_lun_acl too. So a better solution is to remove
that NULLing.
Link: https://lore.kernel.org/r/20220727214125.19647-2-d.bogdanov@yadro.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/target')
| -rw-r--r-- | drivers/target/target_core_device.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 086ac9c9343c..88a844ae1fd0 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -434,9 +434,6 @@ void core_disable_device_list_for_node( kref_put(&orig->pr_kref, target_pr_kref_release); wait_for_completion(&orig->pr_comp); - rcu_assign_pointer(orig->se_lun, NULL); - rcu_assign_pointer(orig->se_lun_acl, NULL); - kfree_rcu(orig, rcu_head); core_scsi3_free_pr_reg_from_nacl(dev, nacl); |