From patchwork Thu Mar 28 19:00:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. 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Wysocki" To: Linux PM Cc: LKML , Srinivas Pandruvada Subject: [Update][PATCH v1.2 4/5] cpufreq: intel_pstate: Get rid of unnecessary READ_ONCE() annotations Date: Thu, 28 Mar 2024 20:00:35 +0100 Message-ID: <12435759.O9o76ZdvQC@kreacher> In-Reply-To: <12420098.O9o76ZdvQC@kreacher> References: <12409658.O9o76ZdvQC@kreacher> <2184891.irdbgypaU6@kreacher> <12420098.O9o76ZdvQC@kreacher> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CLIENT-IP: 195.136.19.94 X-CLIENT-HOSTNAME: 195.136.19.94 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvledrudduledguddukecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfjqffogffrnfdpggftiffpkfenuceurghilhhouhhtmecuudehtdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefufffkjghfggfgtgesthfuredttddtjeenucfhrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqeenucggtffrrghtthgvrhhnpedvffeuiedtgfdvtddugeeujedtffetteegfeekffdvfedttddtuefhgeefvdejhfenucfkphepudelhedrudefiedrudelrdelgeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeduleehrddufeeirdduledrleegpdhhvghlohepkhhrvggrtghhvghrrdhlohgtrghlnhgvthdpmhgrihhlfhhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqpdhnsggprhgtphhtthhopeefpdhrtghpthhtoheplhhinhhugidqphhmsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepshhrihhnihhvrghsrdhprghnughruhhvrggurgeslhhinhhugidrihhnthgvlhdrtghomh X-DCC--Metrics: v370.home.net.pl 1024; Body=3 Fuz1=3 Fuz2=3 From: Rafael J. Wysocki Drop two redundant checks involving READ_ONCE() from notify_hwp_interrupt() and make it check hwp_active without READ_ONCE() which is not necessary, because that variable is only set once during the early initialization of the driver. In order to make that clear, annotate hwp_active with __ro_after_init. Signed-off-by: Rafael J. Wysocki --- v1.1 -> v1.2: Fix uninitialized memory access introduced in v1.1. --- drivers/cpufreq/intel_pstate.c | 27 +++++---------------------- 1 file changed, 5 insertions(+), 22 deletions(-) Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -292,7 +292,7 @@ struct pstate_funcs { static struct pstate_funcs pstate_funcs __read_mostly; -static int hwp_active __read_mostly; +static bool hwp_active __ro_after_init; static int hwp_mode_bdw __read_mostly; static bool per_cpu_limits __read_mostly; static bool hwp_boost __read_mostly; @@ -1636,11 +1636,10 @@ static cpumask_t hwp_intr_enable_mask; void notify_hwp_interrupt(void) { unsigned int this_cpu = smp_processor_id(); - struct cpudata *cpudata; unsigned long flags; u64 value; - if (!READ_ONCE(hwp_active) || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) + if (!hwp_active || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) return; rdmsrl_safe(MSR_HWP_STATUS, &value); @@ -1652,24 +1651,8 @@ void notify_hwp_interrupt(void) if (!cpumask_test_cpu(this_cpu, &hwp_intr_enable_mask)) goto ack_intr; - /* - * Currently we never free all_cpu_data. And we can't reach here - * without this allocated. But for safety for future changes, added - * check. - */ - if (unlikely(!READ_ONCE(all_cpu_data))) - goto ack_intr; - - /* - * The free is done during cleanup, when cpufreq registry is failed. - * We wouldn't be here if it fails on init or switch status. But for - * future changes, added check. - */ - cpudata = READ_ONCE(all_cpu_data[this_cpu]); - if (unlikely(!cpudata)) - goto ack_intr; - - schedule_delayed_work(&cpudata->hwp_notify_work, msecs_to_jiffies(10)); + schedule_delayed_work(&all_cpu_data[this_cpu]->hwp_notify_work, + msecs_to_jiffies(10)); spin_unlock_irqrestore(&hwp_notify_lock, flags); @@ -3464,7 +3447,7 @@ static int __init intel_pstate_init(void * deal with it. */ if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || hwp_forced) { - WRITE_ONCE(hwp_active, 1); + hwp_active = true; hwp_mode_bdw = id->driver_data; intel_pstate.attr = hwp_cpufreq_attrs; intel_cpufreq.attr = hwp_cpufreq_attrs;