6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Cc: Nathan Chancellor <nathan@xxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Audra Mitchell <audra@xxxxxxxxxx> Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@xxxxxxxxxxxxx/ Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/workqueue.c | 64 +++++++++++++++++++---------------------------------- 1 file changed, 24 insertions(+), 40 deletions(-) --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -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 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 w "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_un /* 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 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 workque /* 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 workque 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 wo 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_workque 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_ 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(); }
