devcoredump: Send uevent once devcd is ready

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>

driver core: class: mark the struct class for sysfs callbacks as constant

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>

drivers: remove struct module * setting from struct class

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>

devcoredump : Serialize devcd_del work

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>

Revert "devcoredump: remove the useless gfp_t parameter in dev_coredumpv and dev_coredumpm"

This reverts commit 77515ebaf01920e2db49e04672ef669a7c2907f2 as it
causes build problems in linux-next. It needs to be reintroduced in a
way that can allow the api to evolve and not require a "flag day" to
catch all users.

Link: https://lore.kernel.org/r/20220623160723.7a44b573@canb.auug.org.au
Cc: Duoming Zhou <duoming@zju.edu.cn>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

devcoredump: remove the useless gfp_t parameter in dev_coredumpv and dev_coredumpm

The dev_coredumpv() and dev_coredumpm() could not be used in atomic
context, because they call kvasprintf_const() and kstrdup() with
GFP_KERNEL parameter. The process is shown below:

dev_coredumpv(.., gfp_t gfp)
dev_coredumpm(.., gfp_t gfp)
dev_set_name
kobject_set_name_vargs
kvasprintf_const(GFP_KERNEL, ...); //may sleep
kstrdup(s, GFP_KERNEL); //may sleep

This patch removes gfp_t parameter of dev_coredumpv() and dev_coredumpm()
and changes the gfp_t parameter of kzalloc() in dev_coredumpm() to
GFP_KERNEL in order to show they could not be used in atomic context.

Fixes: 833c95456a70 ("device coredump: add new device coredump class")
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/df72af3b1862bac7d8e793d1f3931857d3779dfd.1654569290.git.duoming@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

devcoredump: remove contact information

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>

devcoredump: fix kernel-doc warning

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>

devcoredump: avoid -Wempty-body warnings

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>

drivers core: Miscellaneous changes for sysfs_emit

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>

devcoredump: fix typo in comment

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>

devcoredump: use memory_read_from_buffer

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>

driver core: Remove redundant license text

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>

driver core: add SPDX identifiers to all driver core files

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>

driver core: devcoredump: convert to use class_groups

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>

devcoredump: add scatterlist support

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>

devcoredump: provide a one-way disable function

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>

device coredump: add new device coredump class

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>