firewire: core: reduce critical section duration in pre-processing of isoc resource...

It is preferable for the critical section to be as small as possible.
Current implementation of iso_resource_auto_work() function uses a
spinlock to control concurrent access to members of fw_card, fw_device,
iso_resource_auto structures, however the locking duration could be
reduced.

This commit refactors to shorten that duration.

Link: https://lore.kernel.org/r/20260501135823.241940-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index bcfb20b770df5c2597f6e413500720a8e012b770..887783e4bd52239bdcf9f139d3ff0045f02db852 100644 (file)
--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -1329,32 +1329,36 @@ static void iso_resource_auto_work(struct work_struct *work)
        struct iso_resource_auto *r = from_work(r, work, work.work);
        struct client *client = r->client;
        unsigned long index = r->resource.handle;
-       int generation, channel, bandwidth, todo;
+       int current_generation, resource_generation, channel, bandwidth, todo;
+       u64 reset_jiffies;
        bool skip, free, success;
 
        scoped_guard(spinlock_irq, &client->lock) {
-               generation = client->device->generation;
+               reset_jiffies = client->device->card->reset_jiffies;
+               current_generation = client->device->generation;
+               resource_generation = r->params.generation;
+               r->params.generation = current_generation;
                todo = r->todo;
-               // Allow 1000ms grace period for other reallocations.
-               if (todo == ISO_RES_AUTO_ALLOC &&
-                   time_is_after_jiffies64(client->device->card->reset_jiffies + secs_to_jiffies(1))) {
-                       schedule_iso_resource_auto(r, msecs_to_jiffies(333));
-                       skip = true;
-               } else {
-                       // We could be called twice within the same generation.
-                       skip = todo == ISO_RES_AUTO_REALLOC &&
-                              r->params.generation == generation;
-               }
-               free = todo == ISO_RES_AUTO_DEALLOC;
-               r->params.generation = generation;
        }
 
+       // Allow 1000ms grace period for other reallocations.
+       if (todo == ISO_RES_AUTO_ALLOC &&
+           time_is_after_jiffies64(reset_jiffies + secs_to_jiffies(1))) {
+               schedule_iso_resource_auto(r, msecs_to_jiffies(333));
+               skip = true;
+       } else {
+               // We could be called twice within the same generation.
+               skip = todo == ISO_RES_AUTO_REALLOC &&
+                      resource_generation == current_generation;
+       }
+       free = todo == ISO_RES_AUTO_DEALLOC;
+
        if (skip)
                goto out;
 
        bandwidth = r->params.bandwidth;
 
-       fw_iso_resource_manage(client->device->card, generation,
+       fw_iso_resource_manage(client->device->card, current_generation,
                        r->params.channels, &channel, &bandwidth,
                        todo == ISO_RES_AUTO_ALLOC ||
                        todo == ISO_RES_AUTO_REALLOC);