From: Rafael J. Wysocki Date: Fri, 5 Sep 2025 13:52:03 +0000 (+0200) Subject: cpufreq: intel_pstate: Fix object lifecycle issue in update_qos_request() X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=69e5d50fcf4093fb3f9f41c4f931f12c2ca8c467;p=users%2Fhch%2Fmisc.git cpufreq: intel_pstate: Fix object lifecycle issue in update_qos_request() 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: da5c504c7aae ("cpufreq: intel_pstate: Implement QoS supported freq constraints") Cc: 5.4+ # 5.4+ Signed-off-by: Rafael J. Wysocki Reviewed-by: Zihuan Zhang Link: https://patch.msgid.link/2255671.irdbgypaU6@rafael.j.wysocki --- diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index e9fe5dd6c792..4cb5e40dd264 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -1667,10 +1667,10 @@ 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_cap(cpu); @@ -1686,6 +1686,8 @@ 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); } }