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From: Dmitry Bogdanov <d.bogdanov@yadro.com>
To: Mike Christie <michael.christie@oracle.com>
Cc: <mlombard@redhat.com>, <martin.petersen@oracle.com>,
	<mgurtovoy@nvidia.com>, <sagi@grimberg.me>,
	<linux-scsi@vger.kernel.org>, <target-devel@vger.kernel.org>
Subject: Re: [PATCH v3 07/14] scsi: target: Fix multiple LUN_RESET handling
Date: Sat, 11 Feb 2023 11:59:22 +0300	[thread overview]
Message-ID: <20230211085922.GA5419@yadro.com> (raw)
In-Reply-To: <20230129234441.116310-8-michael.christie@oracle.com>

On Sun, Jan 29, 2023 at 05:44:34PM -0600, Mike Christie wrote:
> 
> This fixes a bug where an initiator thinks a LUN_RESET has cleaned
> up running commands when it hasn't. The bug was added in:
> 
> commit 51ec502a3266 ("target: Delete tmr from list before processing")
> 
> The problem occurs when:
> 
> 1. We have N IO cmds running in the target layer spread over 2 sessions.
> 2. The initiator sends a LUN_RESET for each session.
> 3. session1's LUN_RESET loops over all the running commands from both
> sessions and moves them to its local drain_task_list.
> 4. session2's LUN_RESET does not see the LUN_RESET from session1 because
> the commit above has it remove itself. session2 also does not see any
> commands since the other reset moved them off the state lists.
> 5. sessions2's LUN_RESET will then complete with a successful response.
> 6. sessions2's inititor believes the running commands on its session are
> now cleaned up due to the successful response and cleans up the running
> commands from its side. It then restarts them.
> 7. The commands do eventually complete on the backend and the target
> starts to return aborted task statuses for them. The initiator will
> either throw a invalid ITT error or might accidentally lookup a new task
> if the ITT has been reallocated already.
> 
> This fixes the bug by reverting the patch.
> 
> Fixes: 51ec502a3266 ("target: Delete tmr from list before processing")
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>

Actually, this patch even fixes a crash that we've just faced.
The second LUN_RESET moves the first LUN_RESET from tmr_list to its
drain_tmr_list, then the first LUN_RESET removes itself from second`s
drain_tmr_list, then the second LUN_RESET tries to remove the first from
the list and crashes because it was deleted already.
So,

Tested-by: Dmitry Bogdanov <d.bogdanov@yadro.com>


  reply	other threads:[~2023-02-11  9:01 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-29 23:44 [PATCH v3 00/14] target: TMF and recovery fixes Mike Christie
2023-01-29 23:44 ` [PATCH v3 01/14] scsi: target: Move sess cmd counter to new struct Mike Christie
2023-03-07 10:53   ` Maurizio Lombardi
2023-01-29 23:44 ` [PATCH v3 02/14] scsi: target: Move cmd counter allocation Mike Christie
2023-01-29 23:44 ` [PATCH v3 03/14] scsi: target: Pass in cmd counter to use during cmd setup Mike Christie
2023-01-29 23:44 ` [PATCH v3 04/14] scsi: target: iscsit/isert: Alloc per conn cmd counter Mike Christie
2023-01-29 23:44 ` [PATCH v3 05/14] scsi: target: iscsit: stop/wait on cmds during conn close Mike Christie
2023-03-01 11:57   ` Maurizio Lombardi
2023-01-29 23:44 ` [PATCH v3 06/14] scsi: target: iscsit: Fix TAS handling during conn cleanup Mike Christie
2023-02-14 14:12   ` Maurizio Lombardi
2023-01-29 23:44 ` [PATCH v3 07/14] scsi: target: Fix multiple LUN_RESET handling Mike Christie
2023-02-11  8:59   ` Dmitry Bogdanov [this message]
2023-03-02  9:43     ` Dmitry Bogdanov
2023-03-02 17:29       ` Mike Christie
2023-03-03  9:26         ` Dmitry Bogdanov
2023-03-03 16:52           ` Mike Christie
2023-01-29 23:44 ` [PATCH v3 08/14] scsi: target: Drop t_state_lock use in compare_and_write_post Mike Christie
2023-01-29 23:44 ` [PATCH v3 09/14] scsi: target: Treat CMD_T_FABRIC_STOP like CMD_T_STOP Mike Christie
2023-01-29 23:44 ` [PATCH v3 10/14] scsi: target: iscsit: Add helper to check when cmd has failed Mike Christie
2023-02-27 15:12   ` Maurizio Lombardi
2023-01-29 23:44 ` [PATCH v3 11/14] scsi: target: iscsit: Cleanup isert commands at conn closure Mike Christie
2023-01-29 23:44 ` [PATCH v3 12/14] IB/isert: Fix hang in target_wait_for_cmds Mike Christie
2023-01-29 23:44 ` [PATCH v3 13/14] IB/isert: Fix use after free during conn cleanup Mike Christie
2023-02-27 15:10   ` Maurizio Lombardi
2023-01-29 23:44 ` [PATCH v3 14/14] scsi: target: iscsit: free cmds before session free Mike Christie
2023-02-22 12:26   ` Maurizio Lombardi

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