[PATCH v2 3/7] regulator: push allocations in create_regulator() outside of lock

[Michał Mirosław]

Move all allocations outside of the regulator_lock()ed section.

======================================================
WARNING: possible circular locking dependency detected
5.7.13+ #535 Not tainted
------------------------------------------------------
f2fs_discard-179:7/702 is trying to acquire lock:
c0e5d920 (regulator_list_mutex){+.+.}-{3:3}, at: 
regulator_lock_dependent+0x54/0x2c0

but task is already holding lock:
cb95b080 (&dcc->cmd_lock){+.+.}-{3:3}, at: __issue_discard_cmd+0xec/0x5f8

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

[...]

-> #3 (fs_reclaim){+.+.}-{0:0}:
       fs_reclaim_acquire.part.11+0x40/0x50
       fs_reclaim_acquire+0x24/0x28
       __kmalloc_track_caller+0x54/0x218
       kstrdup+0x40/0x5c
       create_regulator+0xf4/0x368
       regulator_resolve_supply+0x1a0/0x200
       regulator_register+0x9c8/0x163c

[...]

other info that might help us debug this:

Chain exists of:
  regulator_list_mutex --> &sit_i->sentry_lock --> &dcc->cmd_lock

[...]

Cc: sta...@vger.kernel.org
Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking")
Signed-off-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
---
 drivers/regulator/core.c | 53 +++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 25 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 3dd4d4914075..c95397798275 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1553,44 +1553,53 @@ static struct regulator *create_regulator(struct 
regulator_dev *rdev,
                                          const char *supply_name)
 {
        struct regulator *regulator;
-       char buf[REG_STR_SIZE];
-       int err, size;
+       int err;
+
+       if (dev) {
+               char buf[REG_STR_SIZE];
+               int size;
+
+               size = snprintf(buf, REG_STR_SIZE, "%s-%s",
+                               dev->kobj.name, supply_name);
+               if (size >= REG_STR_SIZE)
+                       return NULL;
+
+               supply_name = kstrdup(buf, GFP_KERNEL);
+               if (supply_name == NULL)
+                       return NULL;
+       } else {
+               supply_name = kstrdup_const(supply_name, GFP_KERNEL);
+               if (supply_name == NULL)
+                       return NULL;
+       }
 
        regulator = kzalloc(sizeof(*regulator), GFP_KERNEL);
-       if (regulator == NULL)
+       if (regulator == NULL) {
+               kfree(supply_name);
                return NULL;
+       }
 
-       regulator_lock(rdev);
        regulator->rdev = rdev;
+       regulator->supply_name = supply_name;
+
+       regulator_lock(rdev);
        list_add(&regulator->list, &rdev->consumer_list);
+       regulator_unlock(rdev);
 
        if (dev) {
                regulator->dev = dev;
 
                /* Add a link to the device sysfs entry */
-               size = snprintf(buf, REG_STR_SIZE, "%s-%s",
-                               dev->kobj.name, supply_name);
-               if (size >= REG_STR_SIZE)
-                       goto overflow_err;
-
-               regulator->supply_name = kstrdup(buf, GFP_KERNEL);
-               if (regulator->supply_name == NULL)
-                       goto overflow_err;
-
                err = sysfs_create_link_nowarn(&rdev->dev.kobj, &dev->kobj,
-                                       buf);
+                                              supply_name);
                if (err) {
                        rdev_dbg(rdev, "could not add device link %s err %d\n",
                                  dev->kobj.name, err);
                        /* non-fatal */
                }
-       } else {
-               regulator->supply_name = kstrdup_const(supply_name, GFP_KERNEL);
-               if (regulator->supply_name == NULL)
-                       goto overflow_err;
        }
 
-       regulator->debugfs = debugfs_create_dir(regulator->supply_name,
+       regulator->debugfs = debugfs_create_dir(supply_name,
                                                rdev->debugfs);
        if (!regulator->debugfs) {
                rdev_dbg(rdev, "Failed to create debugfs directory\n");
@@ -1615,13 +1624,7 @@ static struct regulator *create_regulator(struct 
regulator_dev *rdev,
            _regulator_is_enabled(rdev))
                regulator->always_on = true;
 
-       regulator_unlock(rdev);
        return regulator;
-overflow_err:
-       list_del(&regulator->list);
-       kfree(regulator);
-       regulator_unlock(rdev);
-       return NULL;
 }
 
 static int _regulator_get_enable_time(struct regulator_dev *rdev)
-- 
2.20.1