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cpufreq: intel_pstate: Fix object lifecycle issue in update_qos_request()

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commit 69e5d50fcf4093fb3f9f41c4f931f12c2ca8c467 upstream.

The cpufreq_cpu_put() call in update_qos_request() takes place too early
because the latter subsequently calls freq_qos_update_request() that
indirectly accesses the policy object in question through the QoS request
object passed to it.

Fortunately, update_qos_request() is called under intel_pstate_driver_lock,
so this issue does not matter for changing the intel_pstate operation
mode, but it theoretically can cause a crash to occur on CPU device hot
removal (which currently can only happen in virt, but it is formally
supported nevertheless).

Address this issue by modifying update_qos_request() to drop the
reference to the policy later.

Fixes: da5c504c7a ("cpufreq: intel_pstate: Implement QoS supported freq constraints")
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
Link: https://patch.msgid.link/2255671.irdbgypaU6@rafael.j.wysocki
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rafael J. Wysocki 2025-09-05 15:52:03 +02:00 • committed by Greg Kroah-Hartman
commit 15ac9579eb
1 changed files with 5 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

8
drivers/cpufreq/intel_pstate.c
View file

@ -1092,10 +1092,10 @@ static void update_qos_request(enum freq_qos_req_type type)
continue;
req = policy->driver_data;
cpufreq_cpu_put(policy);
if (!req)
if (!req) {
cpufreq_cpu_put(policy);
continue;
}
if (hwp_active)
intel_pstate_get_hwp_max(i, &turbo_max, &max_state);
@ -1114,6 +1114,8 @@ static void update_qos_request(enum freq_qos_req_type type)
if (freq_qos_update_request(req, freq) < 0)
pr_warn("Failed to update freq constraint: CPU%d\n", i);
cpufreq_cpu_put(policy);
}
}