diff options
author | Seyediman Seyedarab <imandevel@gmail.com> | 2025-05-12 21:57:26 -0400 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-05-14 14:41:15 +0200 |
commit | a0982afa0992a9b9ecfe610d6a31fc05bb15a05a (patch) | |
tree | 2f8bc68ac1283a7dd18913a8927126f6f328d52d /scripts/lib/kdoc/kdoc_files.py | |
parent | f20af84c29b222f68df53bfa72dcfbd4a3491603 (diff) |
cpufreq: drop redundant cpus_read_lock() from store_local_boost()
Lockdep reports a possible circular locking dependency [1] when
cpu_hotplug_lock is acquired inside store_local_boost(), after
policy->rwsem has already been taken by store().
However, the boost update is strictly per-policy and does not
access shared state or iterate over all policies.
Since policy->rwsem is already held, this is enough to serialize
against concurrent topology changes for the current policy.
Remove the cpus_read_lock() to resolve the lockdep warning and
avoid unnecessary locking.
[1]
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc6-debug-gb01fc4eca73c #1 Not tainted
------------------------------------------------------
power-profiles-/588 is trying to acquire lock:
ffffffffb3a7d910 (cpu_hotplug_lock){++++}-{0:0}, at: store_local_boost+0x56/0xd0
but task is already holding lock:
ffff8b6e5a12c380 (&policy->rwsem){++++}-{4:4}, at: store+0x37/0x90
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&policy->rwsem){++++}-{4:4}:
down_write+0x29/0xb0
cpufreq_online+0x7e8/0xa40
cpufreq_add_dev+0x82/0xa0
subsys_interface_register+0x148/0x160
cpufreq_register_driver+0x15d/0x260
amd_pstate_register_driver+0x36/0x90
amd_pstate_init+0x1e7/0x270
do_one_initcall+0x68/0x2b0
kernel_init_freeable+0x231/0x270
kernel_init+0x15/0x130
ret_from_fork+0x2c/0x50
ret_from_fork_asm+0x11/0x20
-> #1 (subsys mutex#3){+.+.}-{4:4}:
__mutex_lock+0xc2/0x930
subsys_interface_register+0x7f/0x160
cpufreq_register_driver+0x15d/0x260
amd_pstate_register_driver+0x36/0x90
amd_pstate_init+0x1e7/0x270
do_one_initcall+0x68/0x2b0
kernel_init_freeable+0x231/0x270
kernel_init+0x15/0x130
ret_from_fork+0x2c/0x50
ret_from_fork_asm+0x11/0x20
-> #0 (cpu_hotplug_lock){++++}-{0:0}:
__lock_acquire+0x10ed/0x1850
lock_acquire.part.0+0x69/0x1b0
cpus_read_lock+0x2a/0xc0
store_local_boost+0x56/0xd0
store+0x50/0x90
kernfs_fop_write_iter+0x132/0x200
vfs_write+0x2b3/0x590
ksys_write+0x74/0xf0
do_syscall_64+0xbb/0x1d0
entry_SYSCALL_64_after_hwframe+0x56/0x5e
Signed-off-by: Seyediman Seyedarab <ImanDevel@gmail.com>
Link: https://patch.msgid.link/20250513015726.1497-1-ImanDevel@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'scripts/lib/kdoc/kdoc_files.py')
0 files changed, 0 insertions, 0 deletions