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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0294-sched-Simplify-set_affinity_pending-refcounts.patch | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/debian/patches-rt/0294-sched-Simplify-set_affinity_pending-refcounts.patch b/debian/patches-rt/0294-sched-Simplify-set_affinity_pending-refcounts.patch new file mode 100644 index 000000000..1230259b8 --- /dev/null +++ b/debian/patches-rt/0294-sched-Simplify-set_affinity_pending-refcounts.patch @@ -0,0 +1,129 @@ +From 6681b566fe9ffe9365121a790537ada2e4ef97ba Mon Sep 17 00:00:00 2001 +From: Peter Zijlstra <peterz@infradead.org> +Date: Tue, 8 Jun 2021 00:37:35 -0400 +Subject: [PATCH 294/323] sched: Simplify set_affinity_pending refcounts +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz + +commit 50caf9c14b1498c90cf808dbba2ca29bd32ccba4 upstream. + +Now that we have set_affinity_pending::stop_pending to indicate if a +stopper is in progress, and we have the guarantee that if that stopper +exists, it will (eventually) complete our @pending we can simplify the +refcount scheme by no longer counting the stopper thread. + +Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") +Cc: stable@kernel.org +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Signed-off-by: Ingo Molnar <mingo@kernel.org> +Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> +Link: https://lkml.kernel.org/r/20210224131355.724130207@infradead.org +Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> +Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> +--- + kernel/sched/core.c | 32 ++++++++++++++++++++------------ + 1 file changed, 20 insertions(+), 12 deletions(-) + +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index 76fa3daf1f60..d3b9d69171a2 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -1914,6 +1914,10 @@ struct migration_arg { + struct set_affinity_pending *pending; + }; + ++/* ++ * @refs: number of wait_for_completion() ++ * @stop_pending: is @stop_work in use ++ */ + struct set_affinity_pending { + refcount_t refs; + unsigned int stop_pending; +@@ -2049,10 +2053,6 @@ static int migration_cpu_stop(void *data) + if (complete) + complete_all(&pending->done); + +- /* For pending->{arg,stop_work} */ +- if (pending && refcount_dec_and_test(&pending->refs)) +- wake_up_var(&pending->refs); +- + return 0; + } + +@@ -2251,12 +2251,16 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + push_task = get_task_struct(p); + } + ++ /* ++ * If there are pending waiters, but no pending stop_work, ++ * then complete now. ++ */ + pending = p->migration_pending; +- if (pending) { +- refcount_inc(&pending->refs); ++ if (pending && !pending->stop_pending) { + p->migration_pending = NULL; + complete = true; + } ++ + task_rq_unlock(rq, p, rf); + + if (push_task) { +@@ -2265,7 +2269,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + } + + if (complete) +- goto do_complete; ++ complete_all(&pending->done); + + return 0; + } +@@ -2316,9 +2320,9 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + if (!stop_pending) + pending->stop_pending = true; + +- refcount_inc(&pending->refs); /* pending->{arg,stop_work} */ + if (flags & SCA_MIGRATE_ENABLE) + p->migration_flags &= ~MDF_PUSH; ++ + task_rq_unlock(rq, p, rf); + + if (!stop_pending) { +@@ -2334,12 +2338,13 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + if (task_on_rq_queued(p)) + rq = move_queued_task(rq, rf, p, dest_cpu); + +- p->migration_pending = NULL; +- complete = true; ++ if (!pending->stop_pending) { ++ p->migration_pending = NULL; ++ complete = true; ++ } + } + task_rq_unlock(rq, p, rf); + +-do_complete: + if (complete) + complete_all(&pending->done); + } +@@ -2347,7 +2352,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + wait_for_completion(&pending->done); + + if (refcount_dec_and_test(&pending->refs)) +- wake_up_var(&pending->refs); ++ wake_up_var(&pending->refs); /* No UaF, just an address */ + + /* + * Block the original owner of &pending until all subsequent callers +@@ -2355,6 +2360,9 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag + */ + wait_var_event(&my_pending.refs, !refcount_read(&my_pending.refs)); + ++ /* ARGH */ ++ WARN_ON_ONCE(my_pending.stop_pending); ++ + return 0; + } + +-- +2.43.0 + |