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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Subject: [PATCH v1 1/5] cpufreq: intel_pstate: Drop redundant locking from intel_pstate_driver_cleanup()
Date: Thu, 21 Mar 2024 20:29:43 +0100	[thread overview]
Message-ID: <6035571.lOV4Wx5bFT@kreacher> (raw)
In-Reply-To: <12409658.O9o76ZdvQC@kreacher>

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Remove the spinlock locking from intel_pstate_driver_cleanup() as it is
not necessary because no other code accessing all_cpu_data[] can run in
parallel with that function.

Had the locking been necessary, though, it would have been incorrect
because the lock in question is acquired from a hardirq handler and
it cannot be acquired from thread context without disabling interrupts.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/intel_pstate.c |    2 --
 1 file changed, 2 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -3135,10 +3135,8 @@ static void intel_pstate_driver_cleanup(
 			if (intel_pstate_driver == &intel_pstate)
 				intel_pstate_clear_update_util_hook(cpu);
 
-			spin_lock(&hwp_notify_lock);
 			kfree(all_cpu_data[cpu]);
 			WRITE_ONCE(all_cpu_data[cpu], NULL);
-			spin_unlock(&hwp_notify_lock);
 		}
 	}
 	cpus_read_unlock();




  reply	other threads:[~2024-03-21 19:34 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-21 19:28 [PATCH v1 0/5] intel_pstate: Some code cleanups, mostly related to concurrency Rafael J. Wysocki
2024-03-21 19:29 ` Rafael J. Wysocki [this message]
2024-03-21 19:30 ` [PATCH v1 2/5] cpufreq: intel_pstate: Simplify spinlock locking Rafael J. Wysocki
2024-03-21 19:32 ` [PATCH v1 3/5] cpufreq: intel_pstate: Wait for canceled delayed work to complete Rafael J. Wysocki
2024-03-21 19:33 ` [PATCH v1 4/5] cpufreq: intel_pstate: Get rid of unnecessary READ_ONCE() annotations Rafael J. Wysocki
2024-03-25 16:45   ` [Update][PATCH v1.1 " Rafael J. Wysocki
2024-03-28 19:00     ` [Update][PATCH v1.2 " Rafael J. Wysocki
2024-03-21 19:34 ` [PATCH v1 5/5] cpufreq: intel_pstate: Use __ro_after_init for three variables Rafael J. Wysocki

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