linux-stable.git/drivers/target/iscsi, branch linux-4.19.y Linux kernel stable tree scsi: target: iscsi: Fix buffer overflow in lio_target_nacl_info_show() 2023-09-23T08:48:17+00:00 Konstantin Shelekhin k.shelekhin@yadro.com 2023-07-22T15:26:37+00:00 114b44dddea1f8f99576de3c0e6e9059012002fc [ Upstream commit 801f287c93ff95582b0a2d2163f12870a2f076d4 ] The function lio_target_nacl_info_show() uses sprintf() in a loop to print details for every iSCSI connection in a session without checking for the buffer length. With enough iSCSI connections it's possible to overflow the buffer provided by configfs and corrupt the memory. This patch replaces sprintf() with sysfs_emit_at() that checks for buffer boundries. Signed-off-by: Konstantin Shelekhin <k.shelekhin@yadro.com> Link: https://lore.kernel.org/r/20230722152657.168859-2-k.shelekhin@yadro.com Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 801f287c93ff95582b0a2d2163f12870a2f076d4 ]

The function lio_target_nacl_info_show() uses sprintf() in a loop to print
details for every iSCSI connection in a session without checking for the
buffer length. With enough iSCSI connections it's possible to overflow the
buffer provided by configfs and corrupt the memory.

This patch replaces sprintf() with sysfs_emit_at() that checks for buffer
boundries.

Signed-off-by: Konstantin Shelekhin <k.shelekhin@yadro.com>
Link: https://lore.kernel.org/r/20230722152657.168859-2-k.shelekhin@yadro.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsi: Prevent login threads from racing between each other 2023-06-28T08:15:30+00:00 Maurizio Lombardi mlombard@redhat.com 2023-05-08T16:22:19+00:00 1fb997c59e2ea16564c52a6e77230e913821ecb6 [ Upstream commit 2a737d3b8c792400118d6cf94958f559de9c5e59 ] The tpg->np_login_sem is a semaphore that is used to serialize the login process when multiple login threads run concurrently against the same target portal group. The iscsi_target_locate_portal() function finds the tpg, calls iscsit_access_np() against the np_login_sem semaphore and saves the tpg pointer in conn->tpg; If iscsi_target_locate_portal() fails, the caller will check for the conn->tpg pointer and, if it's not NULL, then it will assume that iscsi_target_locate_portal() called iscsit_access_np() on the semaphore. Make sure that conn->tpg gets initialized only if iscsit_access_np() was successful, otherwise iscsit_deaccess_np() may end up being called against a semaphore we never took, allowing more than one thread to access the same tpg. Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Link: https://lore.kernel.org/r/20230508162219.1731964-4-mlombard@redhat.com Reviewed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2a737d3b8c792400118d6cf94958f559de9c5e59 ]

The tpg->np_login_sem is a semaphore that is used to serialize the login
process when multiple login threads run concurrently against the same
target portal group.

The iscsi_target_locate_portal() function finds the tpg, calls
iscsit_access_np() against the np_login_sem semaphore and saves the tpg
pointer in conn->tpg;

If iscsi_target_locate_portal() fails, the caller will check for the
conn->tpg pointer and, if it's not NULL, then it will assume that
iscsi_target_locate_portal() called iscsit_access_np() on the semaphore.

Make sure that conn->tpg gets initialized only if iscsit_access_np() was
successful, otherwise iscsit_deaccess_np() may end up being called against
a semaphore we never took, allowing more than one thread to access the same
tpg.

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Link: https://lore.kernel.org/r/20230508162219.1731964-4-mlombard@redhat.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsit: Fix TAS handling during conn cleanup 2023-05-17T09:13:12+00:00 Mike Christie michael.christie@oracle.com 2023-03-19T01:56:19+00:00 d62b7d1cb403d0e482ee7626958852dbba909899 [ Upstream commit cc79da306ebb2edb700c3816b90219223182ac3c ] Fix a bug added in commit f36199355c64 ("scsi: target: iscsi: Fix cmd abort fabric stop race"). If CMD_T_TAS is set on the se_cmd we must call iscsit_free_cmd() to do the last put on the cmd and free it, because the connection is down and we will not up sending the response and doing the put from the normal I/O path. Add a check for CMD_T_TAS in iscsit_release_commands_from_conn() so we now detect this case and run iscsit_free_cmd(). Fixes: f36199355c64 ("scsi: target: iscsi: Fix cmd abort fabric stop race") Signed-off-by: Mike Christie <michael.christie@oracle.com> Link: https://lore.kernel.org/r/20230319015620.96006-9-michael.christie@oracle.com Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cc79da306ebb2edb700c3816b90219223182ac3c ]

Fix a bug added in commit f36199355c64 ("scsi: target: iscsi: Fix cmd abort
fabric stop race").

If CMD_T_TAS is set on the se_cmd we must call iscsit_free_cmd() to do the
last put on the cmd and free it, because the connection is down and we will
not up sending the response and doing the put from the normal I/O
path.

Add a check for CMD_T_TAS in iscsit_release_commands_from_conn() so we now
detect this case and run iscsit_free_cmd().

Fixes: f36199355c64 ("scsi: target: iscsi: Fix cmd abort fabric stop race")
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230319015620.96006-9-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsi: Fix an error message in iscsi_check_key() 2023-04-05T09:15:36+00:00 Maurizio Lombardi mlombard@redhat.com 2023-02-14T14:15:56+00:00 9bb3a10418c82927abf197052e41644dd27f1207 [ Upstream commit 6cc55c969b7ce8d85e09a636693d4126c3676c11 ] The first half of the error message is printed by pr_err(), the second half is printed by pr_debug(). The user will therefore see only the first part of the message and will miss some useful information. Link: https://lore.kernel.org/r/20230214141556.762047-1-mlombard@redhat.com Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Reviewed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 6cc55c969b7ce8d85e09a636693d4126c3676c11 ]

The first half of the error message is printed by pr_err(), the second half
is printed by pr_debug(). The user will therefore see only the first part
of the message and will miss some useful information.

Link: https://lore.kernel.org/r/20230214141556.762047-1-mlombard@redhat.com
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsi: Make sure the np under each tpg is unique 2022-02-16T11:51:44+00:00 ZouMingzhe mingzhe.zou@easystack.cn 2022-01-11T05:47:42+00:00 ded80123b84253ecc6c6cfd1fbbbd99f51c984ec [ Upstream commit a861790afaa8b6369eee8a88c5d5d73f5799c0c6 ] iscsit_tpg_check_network_portal() has nested for_each loops and is supposed to return true when a match is found. However, the tpg loop will still continue after existing the tpg_np loop. If this tpg_np is not the last the match value will be changed. Break the outer loop after finding a match and make sure the np under each tpg is unique. Link: https://lore.kernel.org/r/20220111054742.19582-1-mingzhe.zou@easystack.cn Signed-off-by: ZouMingzhe <mingzhe.zou@easystack.cn> Reviewed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit a861790afaa8b6369eee8a88c5d5d73f5799c0c6 ]

iscsit_tpg_check_network_portal() has nested for_each loops and is supposed
to return true when a match is found. However, the tpg loop will still
continue after existing the tpg_np loop. If this tpg_np is not the last the
match value will be changed.

Break the outer loop after finding a match and make sure the np under each
tpg is unique.

Link: https://lore.kernel.org/r/20220111054742.19582-1-mingzhe.zou@easystack.cn
Signed-off-by: ZouMingzhe <mingzhe.zou@easystack.cn>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
cxgb4/chtls/cxgbit: Keeping the max ofld immediate data size same in cxgb4 and ulds 2021-03-04T08:39:36+00:00 Ayush Sawal ayush.sawal@chelsio.com 2021-02-15T11:42:26+00:00 1be15667db84116d4acdc38b5a8c738107060cc8 [ Upstream commit 2355a6773a2cb0d2dce13432dde78497f1d6617b ] The Max imm data size in cxgb4 is not similar to the max imm data size in the chtls. This caused an mismatch in output of is_ofld_imm() of cxgb4 and chtls. So fixed this by keeping the max wreq size of imm data same in both chtls and cxgb4 as MAX_IMM_OFLD_TX_DATA_WR_LEN. As cxgb4's max imm. data value for ofld packets is changed to MAX_IMM_OFLD_TX_DATA_WR_LEN. Using the same in cxgbit also. Fixes: 36bedb3f2e5b8 ("crypto: chtls - Inline TLS record Tx") Signed-off-by: Ayush Sawal <ayush.sawal@chelsio.com> Acked-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2355a6773a2cb0d2dce13432dde78497f1d6617b ]

The Max imm data size in cxgb4 is not similar to the max imm data size
in the chtls. This caused an mismatch in output of is_ofld_imm() of
cxgb4 and chtls. So fixed this by keeping the max wreq size of imm data
same in both chtls and cxgb4 as MAX_IMM_OFLD_TX_DATA_WR_LEN.

As cxgb4's max imm. data value for ofld packets is changed to
MAX_IMM_OFLD_TX_DATA_WR_LEN. Using the same in cxgbit also.

Fixes: 36bedb3f2e5b8 ("crypto: chtls - Inline TLS record Tx")
Signed-off-by: Ayush Sawal <ayush.sawal@chelsio.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsi: Fix cmd abort fabric stop race 2020-12-02T07:48:10+00:00 Mike Christie michael.christie@oracle.com 2020-11-14T01:46:18+00:00 97b5295711ae0a03a5cfaf025d768c6c87a209f6 [ Upstream commit f36199355c64a39fe82cfddc7623d827c7e050da ] Maurizio found a race where the abort and cmd stop paths can race as follows: 1. thread1 runs iscsit_release_commands_from_conn and sets CMD_T_FABRIC_STOP. 2. thread2 runs iscsit_aborted_task and then does __iscsit_free_cmd. It then returns from the aborted_task callout and we finish target_handle_abort and do: target_handle_abort -> transport_cmd_check_stop_to_fabric -> lio_check_stop_free -> target_put_sess_cmd The cmd is now freed. 3. thread1 now finishes iscsit_release_commands_from_conn and runs iscsit_free_cmd while accessing a command we just released. In __target_check_io_state we check for CMD_T_FABRIC_STOP and set the CMD_T_ABORTED if the driver is not cleaning up the cmd because of a session shutdown. However, iscsit_release_commands_from_conn only sets the CMD_T_FABRIC_STOP and does not check to see if the abort path has claimed completion ownership of the command. This adds a check in iscsit_release_commands_from_conn so only the abort or fabric stop path cleanup the command. Link: https://lore.kernel.org/r/1605318378-9269-1-git-send-email-michael.christie@oracle.com Reported-by: Maurizio Lombardi <mlombard@redhat.com> Reviewed-by: Maurizio Lombardi <mlombard@redhat.com> Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f36199355c64a39fe82cfddc7623d827c7e050da ]

Maurizio found a race where the abort and cmd stop paths can race as
follows:

 1. thread1 runs iscsit_release_commands_from_conn and sets
    CMD_T_FABRIC_STOP.

 2. thread2 runs iscsit_aborted_task and then does __iscsit_free_cmd. It
    then returns from the aborted_task callout and we finish
    target_handle_abort and do:

    target_handle_abort -> transport_cmd_check_stop_to_fabric ->
	lio_check_stop_free -> target_put_sess_cmd

    The cmd is now freed.

 3. thread1 now finishes iscsit_release_commands_from_conn and runs
    iscsit_free_cmd while accessing a command we just released.

In __target_check_io_state we check for CMD_T_FABRIC_STOP and set the
CMD_T_ABORTED if the driver is not cleaning up the cmd because of a session
shutdown. However, iscsit_release_commands_from_conn only sets the
CMD_T_FABRIC_STOP and does not check to see if the abort path has claimed
completion ownership of the command.

This adds a check in iscsit_release_commands_from_conn so only the abort or
fabric stop path cleanup the command.

Link: https://lore.kernel.org/r/1605318378-9269-1-git-send-email-michael.christie@oracle.com
Reported-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Maurizio Lombardi <mlombard@redhat.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
scsi: target: iscsi: Fix hang in iscsit_access_np() when getting tpg->np_login_sem 2020-09-17T11:45:29+00:00 Hou Pu houpu@bytedance.com 2020-07-29T13:03:43+00:00 4f78e55daaa2986bc533d1da3e8e7ac9cc3048f5 commit ed43ffea78dcc97db3f561da834f1a49c8961e33 upstream. The iSCSI target login thread might get stuck with the following stack: cat /proc/`pidof iscsi_np`/stack [<0>] down_interruptible+0x42/0x50 [<0>] iscsit_access_np+0xe3/0x167 [<0>] iscsi_target_locate_portal+0x695/0x8ac [<0>] __iscsi_target_login_thread+0x855/0xb82 [<0>] iscsi_target_login_thread+0x2f/0x5a [<0>] kthread+0xfa/0x130 [<0>] ret_from_fork+0x1f/0x30 This can be reproduced via the following steps: 1. Initiator A tries to log in to iqn1-tpg1 on port 3260. After finishing PDU exchange in the login thread and before the negotiation is finished the the network link goes down. At this point A has not finished login and tpg->np_login_sem is held. 2. Initiator B tries to log in to iqn2-tpg1 on port 3260. After finishing PDU exchange in the login thread the target expects to process remaining login PDUs in workqueue context. 3. Initiator A' tries to log in to iqn1-tpg1 on port 3260 from a new socket. A' will wait for tpg->np_login_sem with np->np_login_timer loaded to wait for at most 15 seconds. The lock is held by A so A' eventually times out. 4. Before A' got timeout initiator B gets negotiation failed and calls iscsi_target_login_drop()->iscsi_target_login_sess_out(). The np->np_login_timer is canceled and initiator A' will hang forever. Because A' is now in the login thread, no new login requests can be serviced. Fix this by moving iscsi_stop_login_thread_timer() out of iscsi_target_login_sess_out(). Also remove iscsi_np parameter from iscsi_target_login_sess_out(). Link: https://lore.kernel.org/r/20200729130343.24976-1-houpu@bytedance.com Cc: stable@vger.kernel.org Reviewed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Hou Pu <houpu@bytedance.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ed43ffea78dcc97db3f561da834f1a49c8961e33 upstream.

The iSCSI target login thread might get stuck with the following stack:

cat /proc/`pidof iscsi_np`/stack
[<0>] down_interruptible+0x42/0x50
[<0>] iscsit_access_np+0xe3/0x167
[<0>] iscsi_target_locate_portal+0x695/0x8ac
[<0>] __iscsi_target_login_thread+0x855/0xb82
[<0>] iscsi_target_login_thread+0x2f/0x5a
[<0>] kthread+0xfa/0x130
[<0>] ret_from_fork+0x1f/0x30

This can be reproduced via the following steps:

1. Initiator A tries to log in to iqn1-tpg1 on port 3260. After finishing
   PDU exchange in the login thread and before the negotiation is finished
   the the network link goes down. At this point A has not finished login
   and tpg->np_login_sem is held.

2. Initiator B tries to log in to iqn2-tpg1 on port 3260. After finishing
   PDU exchange in the login thread the target expects to process remaining
   login PDUs in workqueue context.

3. Initiator A' tries to log in to iqn1-tpg1 on port 3260 from a new
   socket. A' will wait for tpg->np_login_sem with np->np_login_timer
   loaded to wait for at most 15 seconds. The lock is held by A so A'
   eventually times out.

4. Before A' got timeout initiator B gets negotiation failed and calls
   iscsi_target_login_drop()->iscsi_target_login_sess_out().  The
   np->np_login_timer is canceled and initiator A' will hang forever.
   Because A' is now in the login thread, no new login requests can be
   serviced.

Fix this by moving iscsi_stop_login_thread_timer() out of
iscsi_target_login_sess_out(). Also remove iscsi_np parameter from
iscsi_target_login_sess_out().

Link: https://lore.kernel.org/r/20200729130343.24976-1-houpu@bytedance.com
Cc: stable@vger.kernel.org
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Hou Pu <houpu@bytedance.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
scsi: target: iscsi: Fix data digest calculation 2020-09-17T11:45:29+00:00 Varun Prakash varun@chelsio.com 2020-08-25T12:35:10+00:00 549a2cac6bc278b7f238a59eeb644205a10a86ca commit 5528d03183fe5243416c706f64b1faa518b05130 upstream. Current code does not consider 'page_off' in data digest calculation. To fix this, add a local variable 'first_sg' and set first_sg.offset to sg->offset + page_off. Link: https://lore.kernel.org/r/1598358910-3052-1-git-send-email-varun@chelsio.com Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1") Cc: <stable@vger.kernel.org> Reviewed-by: Mike Christie <michael.christie@oralce.com> Signed-off-by: Varun Prakash <varun@chelsio.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5528d03183fe5243416c706f64b1faa518b05130 upstream.

Current code does not consider 'page_off' in data digest calculation. To
fix this, add a local variable 'first_sg' and set first_sg.offset to
sg->offset + page_off.

Link: https://lore.kernel.org/r/1598358910-3052-1-git-send-email-varun@chelsio.com
Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1")
Cc: <stable@vger.kernel.org>
Reviewed-by: Mike Christie <michael.christie@oralce.com>
Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
scsi: target: fix hang when multiple threads try to destroy the same iscsi session 2020-04-21T07:03:11+00:00 Maurizio Lombardi mlombard@redhat.com 2020-03-13T17:06:55+00:00 8b0d0d8c725e67dc9607bdf38472c154250e7355 [ Upstream commit 57c46e9f33da530a2485fa01aa27b6d18c28c796 ] A number of hangs have been reported against the target driver; they are due to the fact that multiple threads may try to destroy the iscsi session at the same time. This may be reproduced for example when a "targetcli iscsi/iqn.../tpg1 disable" command is executed while a logout operation is underway. When this happens, two or more threads may end up sleeping and waiting for iscsit_close_connection() to execute "complete(session_wait_comp)". Only one of the threads will wake up and proceed to destroy the session structure, the remaining threads will hang forever. Note that if the blocked threads are somehow forced to wake up with complete_all(), they will try to free the same iscsi session structure destroyed by the first thread, causing double frees, memory corruptions etc... With this patch, the threads that want to destroy the iscsi session will increase the session refcount and will set the "session_close" flag to 1; then they wait for the driver to close the remaining active connections. When the last connection is closed, iscsit_close_connection() will wake up all the threads and will wait for the session's refcount to reach zero; when this happens, iscsit_close_connection() will destroy the session structure because no one is referencing it anymore. INFO: task targetcli:5971 blocked for more than 120 seconds. Tainted: P OE 4.15.0-72-generic #81~16.04.1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. targetcli D 0 5971 1 0x00000080 Call Trace: __schedule+0x3d6/0x8b0 ? vprintk_func+0x44/0xe0 schedule+0x36/0x80 schedule_timeout+0x1db/0x370 ? __dynamic_pr_debug+0x8a/0xb0 wait_for_completion+0xb4/0x140 ? wake_up_q+0x70/0x70 iscsit_free_session+0x13d/0x1a0 [iscsi_target_mod] iscsit_release_sessions_for_tpg+0x16b/0x1e0 [iscsi_target_mod] iscsit_tpg_disable_portal_group+0xca/0x1c0 [iscsi_target_mod] lio_target_tpg_enable_store+0x66/0xe0 [iscsi_target_mod] configfs_write_file+0xb9/0x120 __vfs_write+0x1b/0x40 vfs_write+0xb8/0x1b0 SyS_write+0x5c/0xe0 do_syscall_64+0x73/0x130 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Link: https://lore.kernel.org/r/20200313170656.9716-3-mlombard@redhat.com Reported-by: Matt Coleman <mcoleman@datto.com> Tested-by: Matt Coleman <mcoleman@datto.com> Tested-by: Rahul Kundu <rahul.kundu@chelsio.com> Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 57c46e9f33da530a2485fa01aa27b6d18c28c796 ]

A number of hangs have been reported against the target driver; they are
due to the fact that multiple threads may try to destroy the iscsi session
at the same time. This may be reproduced for example when a "targetcli
iscsi/iqn.../tpg1 disable" command is executed while a logout operation is
underway.

When this happens, two or more threads may end up sleeping and waiting for
iscsit_close_connection() to execute "complete(session_wait_comp)".  Only
one of the threads will wake up and proceed to destroy the session
structure, the remaining threads will hang forever.

Note that if the blocked threads are somehow forced to wake up with
complete_all(), they will try to free the same iscsi session structure
destroyed by the first thread, causing double frees, memory corruptions
etc...

With this patch, the threads that want to destroy the iscsi session will
increase the session refcount and will set the "session_close" flag to 1;
then they wait for the driver to close the remaining active connections.
When the last connection is closed, iscsit_close_connection() will wake up
all the threads and will wait for the session's refcount to reach zero;
when this happens, iscsit_close_connection() will destroy the session
structure because no one is referencing it anymore.

 INFO: task targetcli:5971 blocked for more than 120 seconds.
       Tainted: P           OE    4.15.0-72-generic #81~16.04.1
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 targetcli       D    0  5971      1 0x00000080
 Call Trace:
  __schedule+0x3d6/0x8b0
  ? vprintk_func+0x44/0xe0
  schedule+0x36/0x80
  schedule_timeout+0x1db/0x370
  ? __dynamic_pr_debug+0x8a/0xb0
  wait_for_completion+0xb4/0x140
  ? wake_up_q+0x70/0x70
  iscsit_free_session+0x13d/0x1a0 [iscsi_target_mod]
  iscsit_release_sessions_for_tpg+0x16b/0x1e0 [iscsi_target_mod]
  iscsit_tpg_disable_portal_group+0xca/0x1c0 [iscsi_target_mod]
  lio_target_tpg_enable_store+0x66/0xe0 [iscsi_target_mod]
  configfs_write_file+0xb9/0x120
  __vfs_write+0x1b/0x40
  vfs_write+0xb8/0x1b0
  SyS_write+0x5c/0xe0
  do_syscall_64+0x73/0x130
  entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Link: https://lore.kernel.org/r/20200313170656.9716-3-mlombard@redhat.com
Reported-by: Matt Coleman <mcoleman@datto.com>
Tested-by: Matt Coleman <mcoleman@datto.com>
Tested-by: Rahul Kundu <rahul.kundu@chelsio.com>
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>