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Android kernel source for the Galaxy A52 5G (a52xq)
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Filename Latest commit message Latest commit date
Maurizio Lombardi 8b0d0d8c72 scsi: target: fix hang when multiple threads try to destroy the same iscsi session
[ 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>
2020-04-21 09:03:11 +02:00
arch kvm: x86: Host feature SSBD doesn't imply guest feature SPEC_CTRL_SSBD 2020-04-21 09:03:10 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:48:42 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: api - Fix race condition in crypto_spawn_alg 2020-02-11 04:34:05 -08:00
Documentation ALSA: hda/realtek - Remove now-unnecessary XPS 13 headphone noise fixups 2020-04-17 10:48:45 +02:00
drivers scsi: target: fix hang when multiple threads try to destroy the same iscsi session 2020-04-21 09:03:11 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:21:29 +01:00
fs ext4: do not zeroout extents beyond i_disksize 2020-04-21 09:03:10 +02:00
include scsi: target: fix hang when multiple threads try to destroy the same iscsi session 2020-04-21 09:03:11 +02:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 16:38:49 +01:00
kernel tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation 2020-04-21 09:03:09 +02:00
lib uapi: rename ext2_swab() to swab() and share globally in swab.h 2020-04-17 10:48:43 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm: Use fixed constant in page_frag_alloc instead of size + 1 2020-04-17 10:48:50 +02:00
net net: revert default NAPI poll timeout to 2 jiffies 2020-04-21 09:03:04 +02:00
samples samples/bpf: Don't try to remove user's homedir on clean 2020-02-11 04:34:05 -08:00
scripts scripts/dtc: Remove redundant YYLOC global declaration 2020-04-02 15:28:17 +02:00
security keys: Fix proc_keys_next to increase position index 2020-04-21 09:03:08 +02:00
sound ALSA: usb-audio: Check mapping at creating connector controls, too 2020-04-21 09:03:08 +02:00
tools perf tools: Support Python 3.8+ in Makefile 2020-04-17 10:48:52 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:44:59 +02:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:42:21 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:38:49 +01:00
Makefile Linux 4.19.116 2020-04-17 10:48:55 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.