Hi Andrea
+cc Lucas
On Mon, Jul 22, 2024 at 10:43 AM Andrea Calabrese
<andrea.calabrese@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi all,
>
> just a small push on this, since I received no notifications.
>
> On 13/06/2024 09:26, Andrea Calabrese wrote:
> > Code refactoring using the recent guard and scoped_guard macros
> > for automatic cleanup of the spinlocks. This does not change the
> > effective behaviour of the kernel, but guarantees a cleaned-up exit from
> > each lock, automatically avoiding potential deadlocks.
> >
> > Signed-off-by: Andrea Calabrese <andrea.calabrese@xxxxxxxxxxxxxxxxxxxx>
> >
> > ---
> > Diff from V3: as Greg KH and Lucas Stach noticed, there was a
> > behavioural change between the two versions: I used guard(spinlock),
> > while the expected behaviour should have come from a spinlock_irqsave
> > guard. This has been fixed.
> >
Maybe you should just repost to get some attention
Michael
> > diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> > index 3df0025d12aa..4872756426dd 100644
> > --- a/drivers/base/devres.c
> > +++ b/drivers/base/devres.c
> > @@ -194,14 +194,12 @@ void devres_for_each_res(struct device *dev, dr_release_t release,
> > {
> > struct devres_node *node;
> > struct devres_node *tmp;
> > - unsigned long flags;
> >
> > if (!fn)
> > return;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > - list_for_each_entry_safe_reverse(node, tmp,
> > - &dev->devres_head, entry) {
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> > + list_for_each_entry_safe_reverse(node, tmp, &dev->devres_head, entry) {
> > struct devres *dr = container_of(node, struct devres, node);
> >
> > if (node->release != release)
> > @@ -210,7 +208,6 @@ void devres_for_each_res(struct device *dev, dr_release_t release,
> > continue;
> > fn(dev, dr->data, data);
> > }
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > }
> > EXPORT_SYMBOL_GPL(devres_for_each_res);
> >
> > @@ -243,11 +240,9 @@ EXPORT_SYMBOL_GPL(devres_free);
> > void devres_add(struct device *dev, void *res)
> > {
> > struct devres *dr = container_of(res, struct devres, data);
> > - unsigned long flags;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> > add_dr(dev, &dr->node);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > }
> > EXPORT_SYMBOL_GPL(devres_add);
> >
> > @@ -287,11 +282,8 @@ void * devres_find(struct device *dev, dr_release_t release,
> > dr_match_t match, void *match_data)
> > {
> > struct devres *dr;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> > dr = find_dr(dev, release, match, match_data);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> >
> > if (dr)
> > return dr->data;
> > @@ -318,16 +310,14 @@ void * devres_get(struct device *dev, void *new_res,
> > {
> > struct devres *new_dr = container_of(new_res, struct devres, data);
> > struct devres *dr;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > - dr = find_dr(dev, new_dr->node.release, match, match_data);
> > - if (!dr) {
> > - add_dr(dev, &new_dr->node);
> > - dr = new_dr;
> > - new_res = NULL;
> > + scoped_guard(spinlock_irqsave, &dev->devres_lock) {
> > + dr = find_dr(dev, new_dr->node.release, match, match_data);
> > + if (!dr) {
> > + add_dr(dev, &new_dr->node);
> > + dr = new_dr;
> > + new_res = NULL;
> > + }
> > }
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > devres_free(new_res);
> >
> > return dr->data;
> > @@ -353,15 +343,13 @@ void * devres_remove(struct device *dev, dr_release_t release,
> > dr_match_t match, void *match_data)
> > {
> > struct devres *dr;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > - dr = find_dr(dev, release, match, match_data);
> > - if (dr) {
> > - list_del_init(&dr->node.entry);
> > - devres_log(dev, &dr->node, "REM");
> > + scoped_guard(spinlock_irqsave, &dev->devres_lock) {
> > + dr = find_dr(dev, release, match, match_data);
> > + if (dr) {
> > + list_del_init(&dr->node.entry);
> > + devres_log(dev, &dr->node, "REM");
> > + }
> > }
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> >
> > if (dr)
> > return dr->data;
> > @@ -516,7 +504,6 @@ static void release_nodes(struct device *dev, struct list_head *todo)
> > */
> > int devres_release_all(struct device *dev)
> > {
> > - unsigned long flags;
> > LIST_HEAD(todo);
> > int cnt;
> >
> > @@ -528,9 +515,9 @@ int devres_release_all(struct device *dev)
> > if (list_empty(&dev->devres_head))
> > return 0;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > - cnt = remove_nodes(dev, dev->devres_head.next, &dev->devres_head, &todo);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > + scoped_guard(spinlock_irqsave, &dev->devres_lock) {
> > + cnt = remove_nodes(dev, dev->devres_head.next, &dev->devres_head, &todo);
> > + }
> >
> > release_nodes(dev, &todo);
> > return cnt;
> > @@ -552,7 +539,6 @@ int devres_release_all(struct device *dev)
> > void * devres_open_group(struct device *dev, void *id, gfp_t gfp)
> > {
> > struct devres_group *grp;
> > - unsigned long flags;
> >
> > grp = kmalloc(sizeof(*grp), gfp);
> > if (unlikely(!grp))
> > @@ -568,9 +554,8 @@ void * devres_open_group(struct device *dev, void *id, gfp_t gfp)
> > if (id)
> > grp->id = id;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> > add_dr(dev, &grp->node[0]);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > return grp->id;
> > }
> > EXPORT_SYMBOL_GPL(devres_open_group);
> > @@ -609,17 +594,14 @@ static struct devres_group * find_group(struct device *dev, void *id)
> > void devres_close_group(struct device *dev, void *id)
> > {
> > struct devres_group *grp;
> > - unsigned long flags;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> >
> > grp = find_group(dev, id);
> > if (grp)
> > add_dr(dev, &grp->node[1]);
> > else
> > WARN_ON(1);
> > -
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > }
> > EXPORT_SYMBOL_GPL(devres_close_group);
> >
> > @@ -635,19 +617,16 @@ EXPORT_SYMBOL_GPL(devres_close_group);
> > void devres_remove_group(struct device *dev, void *id)
> > {
> > struct devres_group *grp;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > -
> > - grp = find_group(dev, id);
> > - if (grp) {
> > - list_del_init(&grp->node[0].entry);
> > - list_del_init(&grp->node[1].entry);
> > - devres_log(dev, &grp->node[0], "REM");
> > - } else
> > - WARN_ON(1);
> >
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > + scoped_guard(spinlock_irqsave, &dev->devres_lock) {
> > + grp = find_group(dev, id);
> > + if (grp) {
> > + list_del_init(&grp->node[0].entry);
> > + list_del_init(&grp->node[1].entry);
> > + devres_log(dev, &grp->node[0], "REM");
> > + } else
> > + WARN_ON(1);
> > + }
> >
> > kfree(grp);
> > }
> > @@ -668,11 +647,10 @@ EXPORT_SYMBOL_GPL(devres_remove_group);
> > int devres_release_group(struct device *dev, void *id)
> > {
> > struct devres_group *grp;
> > - unsigned long flags;
> > LIST_HEAD(todo);
> > int cnt = 0;
> >
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + guard(spinlock_irqsave)(&dev->devres_lock);
> >
> > grp = find_group(dev, id);
> > if (grp) {
> > @@ -683,12 +661,9 @@ int devres_release_group(struct device *dev, void *id)
> > end = grp->node[1].entry.next;
> >
> > cnt = remove_nodes(dev, first, end, &todo);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > -
> > release_nodes(dev, &todo);
> > } else {
> > WARN_ON(1);
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > }
> >
> > return cnt;
> > @@ -860,7 +835,6 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
> > {
> > size_t total_new_size, total_old_size;
> > struct devres *old_dr, *new_dr;
> > - unsigned long flags;
> >
> > if (unlikely(!new_size)) {
> > devm_kfree(dev, ptr);
> > @@ -906,20 +880,17 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
> > * The spinlock protects the linked list against concurrent
> > * modifications but not the resource itself.
> > */
> > - spin_lock_irqsave(&dev->devres_lock, flags);
> > + scoped_guard(spinlock_irqsave, &dev->devres_lock) {
> > + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr);
> > + if (!old_dr) {
> > + kfree(new_dr);
> > + WARN(1, "Memory chunk not managed or managed by a different device.");
> > + return NULL;
> > + }
> >
> > - old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr);
> > - if (!old_dr) {
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > - kfree(new_dr);
> > - WARN(1, "Memory chunk not managed or managed by a different device.");
> > - return NULL;
> > + replace_dr(dev, &old_dr->node, &new_dr->node);
> > }
> >
> > - replace_dr(dev, &old_dr->node, &new_dr->node);
> > -
> > - spin_unlock_irqrestore(&dev->devres_lock, flags);
> > -
> > /*
> > * We can copy the memory contents after releasing the lock as we're
> > * no longer modifying the list links.
>
>
--
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@xxxxxxxxxxxxxxxxxxxx
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