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The original code causes a circular locking dependency found by lockdep.
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 Tainted: G S U
------------------------------------------------------
xe_fault_inject/5091 is trying to acquire lock:
ffff888156815688 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}, at: __flush_work+0x25d/0x660
but task is already holding lock:
ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&devcd->mutex){+.+.}-{3:3}:
mutex_lock_nested+0x4e/0xc0
devcd_data_write+0x27/0x90
sysfs_kf_bin_write+0x80/0xf0
kernfs_fop_write_iter+0x169/0x220
vfs_write+0x293/0x560
ksys_write+0x72/0xf0
__x64_sys_write+0x19/0x30
x64_sys_call+0x2bf/0x2660
do_syscall_64+0x93/0xb60
entry_SYSCALL_64_after_hwframe+0x76/0x7e
-> #1 (kn->active#236){++++}-{0:0}:
kernfs_drain+0x1e2/0x200
__kernfs_remove+0xae/0x400
kernfs_remove_by_name_ns+0x5d/0xc0
remove_files+0x54/0x70
sysfs_remove_group+0x3d/0xa0
sysfs_remove_groups+0x2e/0x60
device_remove_attrs+0xc7/0x100
device_del+0x15d/0x3b0
devcd_del+0x19/0x30
process_one_work+0x22b/0x6f0
worker_thread+0x1e8/0x3d0
kthread+0x11c/0x250
ret_from_fork+0x26c/0x2e0
ret_from_fork_asm+0x1a/0x30
-> #0 ((work_completion)(&(&devcd->del_wk)->work)){+.+.}-{0:0}:
__lock_acquire+0x1661/0x2860
lock_acquire+0xc4/0x2f0
__flush_work+0x27a/0x660
flush_delayed_work+0x5d/0xa0
dev_coredump_put+0x63/0xa0
xe_driver_devcoredump_fini+0x12/0x20 [xe]
devm_action_release+0x12/0x30
release_nodes+0x3a/0x120
devres_release_all+0x8a/0xd0
device_unbind_cleanup+0x12/0x80
device_release_driver_internal+0x23a/0x280
device_driver_detach+0x14/0x20
unbind_store+0xaf/0xc0
drv_attr_store+0x21/0x50
sysfs_kf_write+0x4a/0x80
kernfs_fop_write_iter+0x169/0x220
vfs_write+0x293/0x560
ksys_write+0x72/0xf0
__x64_sys_write+0x19/0x30
x64_sys_call+0x2bf/0x2660
do_syscall_64+0x93/0xb60
entry_SYSCALL_64_after_hwframe+0x76/0x7e
other info that might help us debug this:
Chain exists of: (work_completion)(&(&devcd->del_wk)->work) --> kn->active#236 --> &devcd->mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&devcd->mutex);
lock(kn->active#236);
lock(&devcd->mutex);
lock((work_completion)(&(&devcd->del_wk)->work));
*** DEADLOCK ***
5 locks held by xe_fault_inject/5091:
#0: ffff8881129f9488 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x72/0xf0
#1: ffff88810c755078 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x123/0x220
#2: ffff8881054811a0 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x55/0x280
#3: ffff888156815620 (&devcd->mutex){+.+.}-{3:3}, at: dev_coredump_put+0x3f/0xa0
#4: ffffffff8359e020 (rcu_read_lock){....}-{1:2}, at: __flush_work+0x72/0x660
stack backtrace:
CPU: 14 UID: 0 PID: 5091 Comm: xe_fault_inject Tainted: G S U 6.16.0-rc6-lgci-xe-xe-pw-151626v3+ #1 PREEMPT_{RT,(lazy)}
Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER
Hardware name: Micro-Star International Co., Ltd. MS-7D25/PRO Z690-A DDR4(MS-7D25), BIOS 1.10 12/13/2021
Call Trace:
<TASK>
dump_stack_lvl+0x91/0xf0
dump_stack+0x10/0x20
print_circular_bug+0x285/0x360
check_noncircular+0x135/0x150
? register_lock_class+0x48/0x4a0
__lock_acquire+0x1661/0x2860
lock_acquire+0xc4/0x2f0
? __flush_work+0x25d/0x660
? mark_held_locks+0x46/0x90
? __flush_work+0x25d/0x660
__flush_work+0x27a/0x660
? __flush_work+0x25d/0x660
? trace_hardirqs_on+0x1e/0xd0
? __pfx_wq_barrier_func+0x10/0x10
flush_delayed_work+0x5d/0xa0
dev_coredump_put+0x63/0xa0
xe_driver_devcoredump_fini+0x12/0x20 [xe]
devm_action_release+0x12/0x30
release_nodes+0x3a/0x120
devres_release_all+0x8a/0xd0
device_unbind_cleanup+0x12/0x80
device_release_driver_internal+0x23a/0x280
? bus_find_device+0xa8/0xe0
device_driver_detach+0x14/0x20
unbind_store+0xaf/0xc0
drv_attr_store+0x21/0x50
sysfs_kf_write+0x4a/0x80
kernfs_fop_write_iter+0x169/0x220
vfs_write+0x293/0x560
ksys_write+0x72/0xf0
__x64_sys_write+0x19/0x30
x64_sys_call+0x2bf/0x2660
do_syscall_64+0x93/0xb60
? __f_unlock_pos+0x15/0x20
? __x64_sys_getdents64+0x9b/0x130
? __pfx_filldir64+0x10/0x10
? do_syscall_64+0x1a2/0xb60
? clear_bhb_loop+0x30/0x80
? clear_bhb_loop+0x30/0x80
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x76e292edd574
Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d d5 ea 0e 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89
RSP: 002b:00007fffe247a828 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000076e292edd574
RDX: 000000000000000c RSI: 00006267f6306063 RDI: 000000000000000b
RBP: 000000000000000c R08: 000076e292fc4b20 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00006267f6306063
R13: 000000000000000b R14: 00006267e6859c00 R15: 000076e29322a000
</TASK>
xe 0000:03:00.0: [drm] Xe device coredump has been deleted.
Fixes: 01daccf74832 ("devcoredump : Serialize devcd_del work")
Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # v6.1+
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Cc: Matthew Brost <matthew.brost@intel.com>
Acked-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250723142416.1020423-1-dev@lankhorst.se
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The normal bin_attrs field can now handle const pointers.
This makes the _new variant unnecessary.
Switch all users back.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250530-sysfs-const-bin_attr-final-v3-4-724bfcf05b99@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree
over and remove the historical wrapper inlines.
Conversion was done with coccinelle plus manual fixups where necessary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The sysfs core now allows instances of 'struct bin_attribute' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250114-sysfs-const-bin_attr-devcoredump-v1-2-fa93be30efae@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The macro saves some lines of code and simplifies the constification of
the attribute.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250114-sysfs-const-bin_attr-devcoredump-v1-1-fa93be30efae@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Correct a spello, remove an extra space between words, and fix
one kernel-doc warning:
drivers/base/devcoredump.c:292: warning: No description found for return value of 'devcd_read_from_sgtable'
Fixes: 522566376a3f ("devcoredump: add scatterlist support")
Fixes: 01daccf74832 ("devcoredump : Serialize devcd_del work")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Aviya Erenfeld <aviya.erenfeld@intel.com>
Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Link: https://lore.kernel.org/r/20241130023554.538820-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add function to set a custom coredump timeout.
For Xe driver usage, current 5 minutes timeout may be too short for
users to search and understand what needs to be done to capture
coredump to report bugs.
We have plans to automate(distribute a udev script) it but at the end
will be up to distros and users to pack it so having a option to
increase the timeout is a safer option.
v2:
- replace dev_coredump_timeout_set() by dev_coredumpm_timeout() (Mukesh)
v3:
- make dev_coredumpm() static inline (Johannes)
v5:
- rename DEVCOREDUMP_TIMEOUT -> DEVCD_TIMEOUT to avoid redefinition
in include/net/bluetooth/coredump.h
v6:
- fix definition of dev_coredumpm_timeout() when CONFIG_DEV_COREDUMP
is disabled
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20240611174716.72660-1-jose.souza@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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It is useful for modules that do not want to keep coredump available
after its unload.
Otherwise, the coredump would only be removed after DEVCD_TIMEOUT
seconds.
v2:
- dev_coredump_put() documentation updated (Mukesh)
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240409200206.108452-1-jose.souza@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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dev_coredumpm() creates a devcoredump device and adds it
to the core kernel framework which eventually end up
sending uevent to the user space and later creates a
symbolic link to the failed device. An application
running in userspace may be interested in this symbolic
link to get the name of the failed device.
In a issue scenario, once uevent sent to the user space
it start reading '/sys/class/devcoredump/devcdX/failing_device'
to get the actual name of the device which might not been
created and it is in its path of creation.
To fix this, suppress sending uevent till the failing device
symbolic link gets created and send uevent once symbolic
link is created successfully.
Fixes: 833c95456a70 ("device coredump: add new device coredump class")
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1700232572-25823-1-git-send-email-quic_mojha@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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struct class should never be modified in a sysfs callback as there is
nothing in the structure to modify, and frankly, the structure is almost
never used in a sysfs callback, so mark it as constant to allow struct
class to be moved to read-only memory.
While we are touching all class sysfs callbacks also mark the attribute
as constant as it can not be modified. The bonding code still uses this
structure so it can not be removed from the function callbacks.
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Russ Weight <russell.h.weight@intel.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steve French <sfrench@samba.org>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-cifs@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-rdma@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: netdev@vger.kernel.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230325084537.3622280-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There is no need to manually set the owner of a struct class, as the
registering function does it automatically, so remove all of the
explicit settings from various drivers that did so as it is unneeded.
This allows us to remove this pointer entirely from this structure going
forward.
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313181843.1207845-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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In following scenario(diagram), when one thread X running dev_coredumpm()
adds devcd device to the framework which sends uevent notification to
userspace and another thread Y reads this uevent and call to
devcd_data_write() which eventually try to delete the queued timer that
is not initialized/queued yet.
So, debug object reports some warning and in the meantime, timer is
initialized and queued from X path. and from Y path, it gets reinitialized
again and timer->entry.pprev=NULL and try_to_grab_pending() stucks.
To fix this, introduce mutex and a boolean flag to serialize the behaviour.
cpu0(X) cpu1(Y)
dev_coredump() uevent sent to user space
device_add() ======================> user space process Y reads the
uevents writes to devcd fd
which results into writes to
devcd_data_write()
mod_delayed_work()
try_to_grab_pending()
del_timer()
debug_assert_init()
INIT_DELAYED_WORK()
schedule_delayed_work()
debug_object_fixup()
timer_fixup_assert_init()
timer_setup()
do_init_timer()
/*
Above call reinitializes
the timer to
timer->entry.pprev=NULL
and this will be checked
later in timer_pending() call.
*/
timer_pending()
!hlist_unhashed_lockless(&timer->entry)
!h->pprev
/*
del_timer() checks h->pprev and finds
it to be NULL due to which
try_to_grab_pending() stucks.
*/
Link: https://lore.kernel.org/lkml/2e1f81e2-428c-f11f-ce92-eb11048cb271@quicinc.com/
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Link: https://lore.kernel.org/r/1663073424-13663-1-git-send-email-quic_mojha@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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That email address hasn't existed for a long time, and the
mailing address is pretty useless; remove all of this.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20210528100314.d419f6e8e2d2.Ica8076036c755d6f782becd62d04c41361323130@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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remove make W=1 warnings
drivers/base/devcoredump.c:208: warning:
Function parameter or member 'data' not described in
'devcd_free_sgtable'
drivers/base/devcoredump.c:208: warning:
Excess function parameter 'table' description in 'devcd_free_sgtable'
drivers/base/devcoredump.c:225: warning:
expecting prototype for devcd_read_from_table(). Prototype was for
devcd_read_from_sgtable() instead
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210331232614.304591-8-pierre-louis.bossart@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cleaning out the last -Wempty-body warnings found some interesting
cases with empty macros, along with harmless warnings like this one:
drivers/base/devcoredump.c: In function 'dev_coredumpm':
drivers/base/devcoredump.c:297:56: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
297 | /* nothing - symlink will be missing */;
| ^
drivers/base/devcoredump.c:301:56: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
301 | /* nothing - symlink will be missing */;
| ^
Randy tried addressing this one before, and there were multiple
other ideas in that thread.
Add a runtime warning and code comment here.
Link: https://lore.kernel.org/lkml/20200418184111.13401-8-rdunlap@infradead.org/
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210322114258.3420937-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Change additional instances that could use sysfs_emit and sysfs_emit_at
that the coccinelle script could not convert.
o macros creating show functions with ## concatenation
o unbound sprintf uses with buf+len for start of output to sysfs_emit_at
o returns with ?: tests and sprintf to sysfs_emit
o sysfs output with struct class * not struct device * arguments
Miscellanea:
o remove unnecessary initializations around these changes
o consistently use int len for return length of show functions
o use octal permissions and not S_<FOO>
o rename a few show function names so DEVICE_ATTR_<FOO> can be used
o use DEVICE_ATTR_ADMIN_RO where appropriate
o consistently use const char *output for strings
o checkpatch/style neatening
Signed-off-by: Joe Perches <joe@perches.com>
Link: https://lore.kernel.org/r/8bc24444fe2049a9b2de6127389b57edfdfe324d.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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s/dev_coredumpmsg/dev_coredumpsg/ in the kernel-doc
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/1564243146-5681-3-git-send-email-akinobu.mita@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20190731100007.32684-2-johannes@sipsolutions.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Use memory_read_from_buffer() to simplify devcd_readv().
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/1564243146-5681-2-git-send-email-akinobu.mita@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20190731100007.32684-1-johannes@sipsolutions.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Now that the SPDX tag is in all driver core files, that identifies the
license in a specific and legally-defined manner. So the extra GPL text
wording can be removed as it is no longer needed at all.
This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.
No copyright headers or other non-license-description text was removed.
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.
Update the driver core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.
This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Convert devcoredump to use class_groups instead of class_attrs as that's
the correct way to handle lists of class attribute files.
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add scatterlist support (dev_coredumpsg) to allow drivers to avoid
vmalloc() like dev_coredumpm(), while also avoiding the module
reference that the latter function requires.
This internally uses dev_coredumpm() with function inside the
devcoredump module, requiring removing the const
(which touches the driver using it.)
Signed-off-by: Aviya Erenfeld <aviya.erenfeld@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Since device/firmware coredumps can contain private data, it can
be desirable to turn them off unconditionally to be certain that
no such data will be collected by the system.
To achieve this, provide a "disabled" sysfs class attribute that
can only be changed from 0 to 1 and not back. Upon disabling,
discard existing coredumps and stop storing new ones.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Many devices run firmware and/or complex hardware, and most of that
can have bugs. When it misbehaves, however, it is often much harder
to debug than software running on the host.
Introduce a "device coredump" mechanism to allow dumping internal
device/firmware state through a generalized mechanism. As devices
are different and information needed can vary accordingly, this
doesn't prescribe a file format - it just provides mechanism to
get data to be able to capture it in a generalized way (e.g. in
distributions.)
The dumped data will be readable in sysfs in the virtual device's
data file under /sys/class/devcoredump/devcd*/. Writing to it will
free the data and remove the device, as does a 5-minute timeout.
Note that generalized capturing of such data may result in privacy
issues, so users generally need to be involved. In order to allow
certain users/system integrators/... to disable the feature at all,
introduce a Kconfig option to override the drivers that would like
to have the feature.
For now, this provides two ways of dumping data:
1) with a vmalloc'ed area, that is then given to the subsystem
and freed after retrieval or timeout
2) with a generalized reader/free function method
We could/should add more options, e.g. a list of pages, since the
vmalloc area is very limited on some architectures.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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