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firewire: core: use lock in Xarray instead of local R/W semaphore

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The data of XArray structure includes spinlock and requires no external
lock, while the data is still under the critical section by
fw_device_rwsem.

This commit deletes the critical section.

Link: https://lore.kernel.org/r/20240812014251.165492-3-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
This commit is contained in:
Takashi Sakamoto 2024-08-12 10:42:51 +09:00
parent 7e5a7725a0
commit 7a0a57cff2
1 changed files with 6 additions and 13 deletions
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7
drivers/firewire/core-device.c
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@ -806,7 +806,6 @@ static int shutdown_unit(struct device *device, void *data)
/*
* fw_device_rwsem acts as dual purpose mutex:
* - serializes accesses to fw_device_idr,
* - serializes accesses to fw_device.config_rom/.config_rom_length and
* fw_unit.directory, unless those accesses happen at safe occasions
*/
@ -819,8 +818,6 @@ struct fw_device *fw_device_get_by_devt(dev_t devt)
{
struct fw_device *device;
guard(rwsem_read)(&fw_device_rwsem);
device = xa_load(&fw_device_xa, MINOR(devt));
if (device)
fw_device_get(device);
@ -874,7 +871,6 @@ static void fw_device_shutdown(struct work_struct *work)
device_for_each_child(&device->device, NULL, shutdown_unit);
device_unregister(&device->device);
scoped_guard(rwsem_write, &fw_device_rwsem)
xa_erase(&fw_device_xa, MINOR(device->device.devt));
fw_device_put(device);
@ -1087,12 +1083,10 @@ static void fw_device_init(struct work_struct *work)
fw_device_get(device);
scoped_guard(rwsem_write, &fw_device_rwsem) {
// The index of allocated entry is used for minor identifier of device node.
ret = xa_alloc(&fw_device_xa, &minor, device, XA_LIMIT(0, MINORMASK), GFP_KERNEL);
if (ret < 0)
goto error;
}
device->device.bus = &fw_bus_type;
device->device.type = &fw_device_type;
@ -1152,7 +1146,6 @@ static void fw_device_init(struct work_struct *work)
return;
error_with_cdev:
scoped_guard(rwsem_write, &fw_device_rwsem)
xa_erase(&fw_device_xa, minor);
error:
fw_device_put(device); // fw_device_xa's reference.