[PATCH 2/2] ufs: core: Really fix the code for updating the "hid" attribute group

[Bart Van Assche <bvanassche@acm.org>]

Recently a sysfs_update_group() call was added in ufs_get_device_desc().
ufs_get_device_desc() may be called from the error handler and the error
handler may be activated before ufs_sysfs_add_nodes() is called. This
causes creation of the "hid" directory before ufs_sysfs_add_nodes() is
called and hence causes this function to fail.

Fix this by tracking whether or not ufs_sysfs_add_nodes() has already
been called. This patch fixes the following kernel warning:

sysfs: cannot create duplicate filename '/devices/platform/3c2d0000.ufs/hid'
Workqueue: async async_run_entry_fn
Call trace:
 dump_backtrace+0xfc/0x17c
 show_stack+0x18/0x28
 dump_stack_lvl+0x40/0x104
 dump_stack+0x18/0x3c
 sysfs_warn_dup+0x6c/0xc8
 internal_create_group+0x1c8/0x504
 sysfs_create_groups+0x38/0x9c
 ufs_sysfs_add_nodes+0x20/0x58
 ufshcd_init+0x1114/0x134c
 ufshcd_pltfrm_init+0x728/0x7d8
 ufs_google_probe+0x30/0x84
 platform_probe+0xa0/0xe0
 really_probe+0x114/0x454
 __driver_probe_device+0xa4/0x160
 driver_probe_device+0x44/0x23c
 __device_attach_driver+0x15c/0x1f4
 bus_for_each_drv+0x10c/0x168
 __device_attach_async_helper+0x80/0xf8
 async_run_entry_fn+0x4c/0x17c
 process_one_work+0x26c/0x65c
 worker_thread+0x33c/0x498
 kthread+0x110/0x134
 ret_from_fork+0x10/0x20
ufshcd 3c2d0000.ufs: ufs_sysfs_add_nodes: sysfs groups creation failed (err = -17)

Cc: Daniel Lee <chullee@google.com>
Cc: Peter Wang <peter.wang@mediatek.com>
Fixes: bb7663dec67b ("scsi: ufs: sysfs: Make HID attributes visible")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufs-sysfs.c | 7 ++++++-
 drivers/ufs/core/ufshcd.c    | 3 ++-
 include/ufs/ufshcd.h         | 3 +++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 7150c15287d1..714c611b85b0 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -2095,13 +2095,18 @@ void ufs_sysfs_add_nodes(struct ufs_hba *hba)
 	int ret;
 
 	ret = sysfs_create_groups(&dev->kobj, ufs_sysfs_groups);
-	if (ret)
+	if (ret) {
 		dev_err(dev,
 			"%s: sysfs groups creation failed (err = %d)\n",
 			__func__, ret);
+		return;
+	}
+
+	WRITE_ONCE(hba->sysfs_attrs_added, true);
 }
 
 void ufs_sysfs_remove_nodes(struct ufs_hba *hba)
 {
+	WRITE_ONCE(hba->sysfs_attrs_added, false);
 	sysfs_remove_groups(&hba->dev->kobj, ufs_sysfs_groups);
 }
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9521aa38211c..4a543a2a10a4 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8499,7 +8499,8 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
 				DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP) &
 				UFS_DEV_HID_SUPPORT;
 
-	sysfs_update_group(&hba->dev->kobj, &ufs_sysfs_hid_group);
+	if (READ_ONCE(hba->sysfs_attrs_added))
+		sysfs_update_group(&hba->dev->kobj, &ufs_sysfs_hid_group);
 
 	model_index = desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME];
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 9425cfd9d00e..de7420ee127e 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -869,6 +869,8 @@ enum ufshcd_mcq_opr {
  * @ee_ctrl_mutex: Used to serialize exception event information.
  * @is_powered: flag to check if HBA is powered
  * @shutting_down: flag to check if shutdown has been invoked
+ * @sysfs_attrs_added: Whether or not the sysfs attributes have been added to
+ *	hba->dev.
  * @host_sem: semaphore used to serialize concurrent contexts
  * @eh_wq: Workqueue that eh_work works on
  * @eh_work: Worker to handle UFS errors that require s/w attention
@@ -1021,6 +1023,7 @@ struct ufs_hba {
 	struct mutex ee_ctrl_mutex;
 	bool is_powered;
 	bool shutting_down;
+	bool sysfs_attrs_added;
 	struct semaphore host_sem;
 
 	/* Work Queues */