[PATCH AUTOSEL 6.13 23/31] um: convert irq_lock to raw spinlock

Sasha Levin
2025-02-18T20:25:43Z

From: Johannes Berg <johannes.berg@intel.com>

[ Upstream commit 96178631c3f53398044ed437010f7632ad764bf8 ]

Since this is deep in the architecture, and the code is
called nested into other deep management code, this really
needs to be a raw spinlock. Convert it.

Link: https://patch.msgid.link/20250110125550.32479-8-johannes@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/um/kernel/irq.c | 79 ++++++++++++++++++++++++++------------------
1 file changed, 47 insertions(+), 32 deletions(-)

diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index 338450741aac5..a4991746f5eac 100644
--- a/arch/um/kernel/irq.c
+++ b/arch/um/kernel/irq.c
@@ -52,7 +52,7 @@ struct irq_entry {
bool sigio_workaround;
};

-static DEFINE_SPINLOCK(irq_lock);
+static DEFINE_RAW_SPINLOCK(irq_lock);
static LIST_HEAD(active_fds);
static DECLARE_BITMAP(irqs_allocated, UM_LAST_SIGNAL_IRQ);
static bool irqs_suspended;
@@ -257,7 +257,7 @@ static struct irq_entry *get_irq_entry_by_fd(int fd)
return NULL;
}

-static void free_irq_entry(struct irq_entry *to_free, bool remove)
+static void remove_irq_entry(struct irq_entry *to_free, bool remove)
{
if (!to_free)
return;
@@ -265,7 +265,6 @@ static void free_irq_entry(struct irq_entry *to_free, bool remove)
if (remove)
os_del_epoll_fd(to_free->fd);
list_del(&to_free->list);
- kfree(to_free);
}

static bool update_irq_entry(struct irq_entry *entry)
@@ -286,17 +285,19 @@ static bool update_irq_entry(struct irq_entry *entry)
return false;
}

-static void update_or_free_irq_entry(struct irq_entry *entry)
+static struct irq_entry *update_or_remove_irq_entry(struct irq_entry *entry)
{
- if (!update_irq_entry(entry))
- free_irq_entry(entry, false);
+ if (update_irq_entry(entry))
+ return NULL;
+ remove_irq_entry(entry, false);
+ return entry;
}

static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
void (*timetravel_handler)(int, int, void *,
struct time_travel_event *))
{
- struct irq_entry *irq_entry;
+ struct irq_entry *irq_entry, *to_free = NULL;
int err, events = os_event_mask(type);
unsigned long flags;

@@ -304,9 +305,10 @@ static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
if (err < 0)
goto out;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
irq_entry = get_irq_entry_by_fd(fd);
if (irq_entry) {
+already:
/* cannot register the same FD twice with the same type */
if (WARN_ON(irq_entry->reg[type].events)) {
err = -EALREADY;
@@ -316,11 +318,22 @@ static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
/* temporarily disable to avoid IRQ-side locking */
os_del_epoll_fd(fd);
} else {
- irq_entry = kzalloc(sizeof(*irq_entry), GFP_ATOMIC);
- if (!irq_entry) {
- err = -ENOMEM;
- goto out_unlock;
+ struct irq_entry *new;
+
+ /* don't restore interrupts */
+ raw_spin_unlock(&irq_lock);
+ new = kzalloc(sizeof(*irq_entry), GFP_ATOMIC);
+ if (!new) {
+ local_irq_restore(flags);
+ return -ENOMEM;
}
+ raw_spin_lock(&irq_lock);
+ irq_entry = get_irq_entry_by_fd(fd);
+ if (irq_entry) {
+ to_free = new;
+ goto already;
+ }
+ irq_entry = new;
irq_entry->fd = fd;
list_add_tail(&irq_entry->list, &active_fds);
maybe_sigio_broken(fd);
@@ -339,12 +352,11 @@ static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
#endif

WARN_ON(!update_irq_entry(irq_entry));
- spin_unlock_irqrestore(&irq_lock, flags);
-
- return 0;
+ err = 0;
out_unlock:
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
out:
+ kfree(to_free);
return err;
}

@@ -358,19 +370,20 @@ void free_irq_by_fd(int fd)
struct irq_entry *to_free;
unsigned long flags;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
to_free = get_irq_entry_by_fd(fd);
- free_irq_entry(to_free, true);
- spin_unlock_irqrestore(&irq_lock, flags);
+ remove_irq_entry(to_free, true);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
+ kfree(to_free);
}
EXPORT_SYMBOL(free_irq_by_fd);

static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
{
- struct irq_entry *entry;
+ struct irq_entry *entry, *to_free = NULL;
unsigned long flags;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
list_for_each_entry(entry, &active_fds, list) {
enum um_irq_type i;

@@ -386,12 +399,13 @@ static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)

os_del_epoll_fd(entry->fd);
reg->events = 0;
- update_or_free_irq_entry(entry);
+ to_free = update_or_remove_irq_entry(entry);
goto out;
}
}
out:
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
+ kfree(to_free);
}

void deactivate_fd(int fd, int irqnum)
@@ -402,7 +416,7 @@ void deactivate_fd(int fd, int irqnum)

os_del_epoll_fd(fd);

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
entry = get_irq_entry_by_fd(fd);
if (!entry)
goto out;
@@ -414,9 +428,10 @@ void deactivate_fd(int fd, int irqnum)
entry->reg[i].events = 0;
}

- update_or_free_irq_entry(entry);
+ entry = update_or_remove_irq_entry(entry);
out:
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
+ kfree(entry);

ignore_sigio_fd(fd);
}
@@ -546,7 +561,7 @@ void um_irqs_suspend(void)

irqs_suspended = true;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
list_for_each_entry(entry, &active_fds, list) {
enum um_irq_type t;
bool clear = true;
@@ -579,7 +594,7 @@ void um_irqs_suspend(void)
!__ignore_sigio_fd(entry->fd);
}
}
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
}

void um_irqs_resume(void)
@@ -588,7 +603,7 @@ void um_irqs_resume(void)
unsigned long flags;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
list_for_each_entry(entry, &active_fds, list) {
if (entry->suspended) {
int err = os_set_fd_async(entry->fd);
@@ -602,7 +617,7 @@ void um_irqs_resume(void)
}
}
}
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);

irqs_suspended = false;
send_sigio_to_self();
@@ -613,7 +628,7 @@ static int normal_irq_set_wake(struct irq_data *d, unsigned int on)
struct irq_entry *entry;
unsigned long flags;

- spin_lock_irqsave(&irq_lock, flags);
+ raw_spin_lock_irqsave(&irq_lock, flags);
list_for_each_entry(entry, &active_fds, list) {
enum um_irq_type t;

@@ -628,7 +643,7 @@ static int normal_irq_set_wake(struct irq_data *d, unsigned int on)
}
}
unlock:
- spin_unlock_irqrestore(&irq_lock, flags);
+ raw_spin_unlock_irqrestore(&irq_lock, flags);
return 0;
}
#else
--
2.39.5