linux/drivers/base/devcoredump.c

450 lines
13 KiB

2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
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>
2022-09-13 18:20:24 +05:30
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>
2023-03-25 09:45:37 +01:00
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>
2022-09-13 18:20:24 +05:30
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>
2022-09-13 18:20:24 +05:30
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>
2022-09-13 18:20:24 +05:30
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>
2023-03-25 09:45:37 +01:00
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2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
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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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
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>
2022-09-13 18:20:24 +05:30
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00
2014-09-12 09:01:56 +02:00