Messages in this thread | | | From | Wander Lairson Costa <> | Subject | [PATCH v6 0/3] Introduce put_task_struct_atomic_sleep() | Date | Fri, 14 Apr 2023 09:55:26 -0300 |
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The put_task_struct() function reduces a usage counter and invokes __put_task_struct() when the counter reaches zero.
In the case of __put_task_struct(), it indirectly acquires a spinlock, which operates as a sleeping lock under the PREEMPT_RT configuration. As a result, invoking put_task_struct() within an atomic context is not feasible for real-time (RT) kernels.
To address this issue, this patch series introduces a new function called put_task_struct_atomic_safe(). When compiled with the PREEMPT_RT configuration, this function defers the call to __put_task_struct() to a process context.
Additionally, the patch series rectifies known problematic call sites to ensure smooth functioning.
Changelog =========
v1: * Initial implementation fixing the splat.
v2: * Isolate the logic in its own function. * Fix two more cases caught in review.
v3: * Change __put_task_struct() to handle the issue internally.
v4: * Explain why call_rcu() is safe to call from interrupt context.
v5: * Explain why __put_task_struct() doesn't conflict with put_task_sruct_rcu_user.
v6: * As per Sebastian's review, revert back the implementation of v2 with a distinct function. * Add a check in put_task_struct() to warning when called from a non-sleepable context. * Address more call sites.
Wander Lairson Costa (3): sched/core: warn on call put_task_struct in invalid context sched/task: Add the put_task_struct_atomic_safe() function treewide: replace put_task_struct() witht the atomic safe version
include/linux/sched/task.h | 45 ++++++++++++++++++++++++++++++++++++++ kernel/events/core.c | 6 ++--- kernel/fork.c | 8 +++++++ kernel/locking/rtmutex.c | 10 ++++----- kernel/sched/core.c | 6 ++--- kernel/sched/deadline.c | 16 +++++++------- kernel/sched/rt.c | 4 ++-- 7 files changed, 74 insertions(+), 21 deletions(-)
-- 2.39.2
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