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Revert "workqueue: RCU protect wq->dfl_pwq and implement accessors for it"

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BugLink: https://bugs.launchpad.net/bugs/2060533

This reverts commit 3fb5dbc8bb3759ad0a82d6bf5ed32866c0410a79 which is commit
9f66cff212bb3c1cd25996aaa0dfd0c9e9d8baab upstream.

The workqueue patches backported to 6.8.y caused some reported
regressions, so revert them for now.

Reported-by: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Tejun Heo <tj@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Audra Mitchell <audra@redhat.com>
Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.info/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
This commit is contained in:
Greg Kroah-Hartman
2024-04-03 16:29:17 +02:00
committed by Roxana Nicolescu
parent 976bccb17e
commit 21cccd516e
1 changed files with 24 additions and 40 deletions
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kernel/workqueue.c
+24 -40
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@@ -304,7 +304,7 @@ struct workqueue_struct {
int saved_max_active; /* WQ: saved max_active */
struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */
struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */
struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */
#ifdef CONFIG_SYSFS
struct wq_device *wq_dev; /* I: for sysfs interface */
@@ -635,23 +635,6 @@ static int worker_pool_assign_id(struct worker_pool *pool)
return ret;
}
static struct pool_workqueue __rcu **
unbound_pwq_slot(struct workqueue_struct *wq, int cpu)
{
if (cpu >= 0)
return per_cpu_ptr(wq->cpu_pwq, cpu);
else
return &wq->dfl_pwq;
}
/* @cpu < 0 for dfl_pwq */
static struct pool_workqueue *unbound_pwq(struct workqueue_struct *wq, int cpu)
{
return rcu_dereference_check(*unbound_pwq_slot(wq, cpu),
lockdep_is_held(&wq_pool_mutex) ||
lockdep_is_held(&wq->mutex));
}
static unsigned int work_color_to_flags(int color)
{
return color << WORK_STRUCT_COLOR_SHIFT;
@@ -4341,11 +4324,10 @@ static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu,
"possible intersect\n");
}
/* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */
/* install @pwq into @wq's cpu_pwq and return the old pwq */
static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq,
int cpu, struct pool_workqueue *pwq)
{
struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu);
struct pool_workqueue *old_pwq;
lockdep_assert_held(&wq_pool_mutex);
@@ -4354,8 +4336,8 @@ static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq,
/* link_pwq() can handle duplicate calls */
link_pwq(pwq);
old_pwq = rcu_access_pointer(*slot);
rcu_assign_pointer(*slot, pwq);
old_pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu));
rcu_assign_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu), pwq);
return old_pwq;
}
@@ -4455,11 +4437,14 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);
/* save the previous pwqs and install the new ones */
/* save the previous pwq and install the new one */
for_each_possible_cpu(cpu)
ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu,
ctx->pwq_tbl[cpu]);
ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq);
/* @dfl_pwq might not have been used, ensure it's linked */
link_pwq(ctx->dfl_pwq);
swap(ctx->wq->dfl_pwq, ctx->dfl_pwq);
mutex_unlock(&ctx->wq->mutex);
}
@@ -4569,7 +4554,9 @@ static void wq_update_pod(struct workqueue_struct *wq, int cpu,
/* nothing to do if the target cpumask matches the current pwq */
wq_calc_pod_cpumask(target_attrs, cpu, off_cpu);
if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs))
pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu),
lockdep_is_held(&wq_pool_mutex));
if (wqattrs_equal(target_attrs, pwq->pool->attrs))
return;
/* create a new pwq */
@@ -4587,11 +4574,10 @@ static void wq_update_pod(struct workqueue_struct *wq, int cpu,
use_dfl_pwq:
mutex_lock(&wq->mutex);
pwq = unbound_pwq(wq, -1);
raw_spin_lock_irq(&pwq->pool->lock);
get_pwq(pwq);
raw_spin_unlock_irq(&pwq->pool->lock);
old_pwq = install_unbound_pwq(wq, cpu, pwq);
raw_spin_lock_irq(&wq->dfl_pwq->pool->lock);
get_pwq(wq->dfl_pwq);
raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock);
old_pwq = install_unbound_pwq(wq, cpu, wq->dfl_pwq);
out_unlock:
mutex_unlock(&wq->mutex);
put_pwq_unlocked(old_pwq);
@@ -4629,13 +4615,10 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
cpus_read_lock();
if (wq->flags & __WQ_ORDERED) {
struct pool_workqueue *dfl_pwq;
ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
/* there should only be single pwq for ordering guarantee */
dfl_pwq = rcu_access_pointer(wq->dfl_pwq);
WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node ||
wq->pwqs.prev != &dfl_pwq->pwqs_node),
WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
"ordering guarantee broken for workqueue %s\n", wq->name);
} else {
ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
@@ -4866,7 +4849,7 @@ static bool pwq_busy(struct pool_workqueue *pwq)
if (pwq->nr_in_flight[i])
return true;
if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1))
if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1))
return true;
if (!pwq_is_empty(pwq))
return true;
@@ -4950,12 +4933,13 @@ void destroy_workqueue(struct workqueue_struct *wq)
rcu_read_lock();
for_each_possible_cpu(cpu) {
put_pwq_unlocked(unbound_pwq(wq, cpu));
RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL);
pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu));
RCU_INIT_POINTER(*per_cpu_ptr(wq->cpu_pwq, cpu), NULL);
put_pwq_unlocked(pwq);
}
put_pwq_unlocked(unbound_pwq(wq, -1));
RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL);
put_pwq_unlocked(wq->dfl_pwq);
wq->dfl_pwq = NULL;
rcu_read_unlock();
}