diff options
| author | Takashi Sakamoto <o-takashi@sakamocchi.jp> | 2024-08-12 10:42:51 +0900 |
|---|---|---|
| committer | Takashi Sakamoto <o-takashi@sakamocchi.jp> | 2024-08-12 10:42:51 +0900 |
| commit | 7a0a57cff296bbd90451fbf1f5614ffc48da73cd (patch) | |
| tree | 1b85658b49851b4ebf6f5ab2782c5584c28ea738 | |
| parent | 7e5a7725a0e4030cf37f8b93ff9d4328166a3b85 (diff) | |
| download | lwn-7a0a57cff296bbd90451fbf1f5614ffc48da73cd.tar.gz lwn-7a0a57cff296bbd90451fbf1f5614ffc48da73cd.zip | |
firewire: core: use lock in Xarray instead of local R/W semaphore
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>
| -rw-r--r-- | drivers/firewire/core-device.c | 19 |
1 files changed, 6 insertions, 13 deletions
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c index 9f3276aa463a..32ac0f115793 100644 --- a/drivers/firewire/core-device.c +++ b/drivers/firewire/core-device.c @@ -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); @@ -874,8 +871,7 @@ 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)); + 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; - } + // 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; @@ -1152,8 +1146,7 @@ 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); + xa_erase(&fw_device_xa, minor); error: fw_device_put(device); // fw_device_xa's reference. |