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e8eef69a99
Pointless overhead to use a work queue to reset the static key for a DO_ONCE_SLEEPABLE() invocation. Note that the previous code path included a BUG_ON() if the static key was already disabled. Dropped that as part of this change because: 1) Use of BUG_ON() is highly discouraged. 2) There is a WARN_ON() in the static_branch_disable() code path that would provide adequate breadcrumbs to debug any issue. Link: https://lkml.kernel.org/r/aWU4tfTju1l3oZCu@agluck-desk3 Signed-off-by: Tony Luck <tony.luck@intel.com> Reported-by: Reinette Chatre <reinette.chatre@intel.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
98 lines
2.2 KiB
C
98 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/once.h>
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#include <linux/random.h>
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#include <linux/module.h>
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struct once_work {
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struct work_struct work;
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struct static_key_true *key;
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struct module *module;
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};
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static void once_deferred(struct work_struct *w)
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{
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struct once_work *work;
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work = container_of(w, struct once_work, work);
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BUG_ON(!static_key_enabled(work->key));
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static_branch_disable(work->key);
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module_put(work->module);
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kfree(work);
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}
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static void once_disable_jump(struct static_key_true *key, struct module *mod)
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{
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struct once_work *w;
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w = kmalloc(sizeof(*w), GFP_ATOMIC);
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if (!w)
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return;
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INIT_WORK(&w->work, once_deferred);
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w->key = key;
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w->module = mod;
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__module_get(mod);
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schedule_work(&w->work);
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}
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static DEFINE_SPINLOCK(once_lock);
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bool __do_once_start(bool *done, unsigned long *flags)
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__acquires(once_lock)
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{
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spin_lock_irqsave(&once_lock, *flags);
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if (*done) {
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spin_unlock_irqrestore(&once_lock, *flags);
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/* Keep sparse happy by restoring an even lock count on
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* this lock. In case we return here, we don't call into
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* __do_once_done but return early in the DO_ONCE() macro.
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*/
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__acquire(once_lock);
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return false;
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}
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return true;
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}
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EXPORT_SYMBOL(__do_once_start);
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void __do_once_done(bool *done, struct static_key_true *once_key,
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unsigned long *flags, struct module *mod)
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__releases(once_lock)
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{
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*done = true;
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spin_unlock_irqrestore(&once_lock, *flags);
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once_disable_jump(once_key, mod);
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}
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EXPORT_SYMBOL(__do_once_done);
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static DEFINE_MUTEX(once_mutex);
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bool __do_once_sleepable_start(bool *done)
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__acquires(once_mutex)
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{
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mutex_lock(&once_mutex);
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if (*done) {
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mutex_unlock(&once_mutex);
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/* Keep sparse happy by restoring an even lock count on
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* this mutex. In case we return here, we don't call into
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* __do_once_done but return early in the DO_ONCE_SLEEPABLE() macro.
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*/
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__acquire(once_mutex);
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return false;
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}
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return true;
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}
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EXPORT_SYMBOL(__do_once_sleepable_start);
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void __do_once_sleepable_done(bool *done, struct static_key_true *once_key,
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struct module *mod)
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__releases(once_mutex)
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{
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*done = true;
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mutex_unlock(&once_mutex);
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static_branch_disable(once_key);
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}
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EXPORT_SYMBOL(__do_once_sleepable_done);
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