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[85.130.200.168]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606c0d0947sm1727493f8f.16.2026.06.11.13.47.01 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 11 Jun 2026 13:47:02 -0700 (PDT) From: Elazar Leibovich To: linux-pm@vger.kernel.org Cc: "Rafael J . Wysocki" , Daniel Lezcano , linux-kernel@vger.kernel.org, Sivan Zohar-Kotzer , Elazar Leibovich Subject: [PATCH 1/2] powercap: dtpm_cpu: Guard em_cpu_get() against NULL return in sysfs callbacks Date: Thu, 11 Jun 2026 23:46:57 +0300 Message-ID: <20260611204658.47987-2-elazarl@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260611204658.47987-1-elazarl@gmail.com> References: <20260611204658.47987-1-elazarl@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Sivan Zohar-Kotzer em_cpu_get() can return NULL when the CPU has no energy model registered (e.g. during hotplug races or initialization failures). Two call sites miss the NULL test: 1. set_pd_power_limit() — reachable from sysfs via the powercap constraint power_limit_uw store path. If NULL, return the current power limit unchanged (no-op) instead of crashing. 2. update_pd_power_uw() — called from CPU hotplug handlers via dtpm_update_power(). Return -EINVAL if the EM is absent, since this is an internal consistency failure that should not be swallowed. The other sysfs-reachable path, get_pd_power_uw(), already has a NULL guard returning 0. Fixes: 0e8f68d7f048 ("powercap/drivers/dtpm: Add CPU energy model based support") Signed-off-by: Sivan Zohar-Kotzer Co-developed-by: Elazar Leibovich Signed-off-by: Elazar Leibovich --- drivers/powercap/dtpm_cpu.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c index 99390ec1481f..0a460f97bf15 100644 --- a/drivers/powercap/dtpm_cpu.c +++ b/drivers/powercap/dtpm_cpu.c @@ -47,6 +47,9 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit) u64 power; int i, nr_cpus; + if (!pd) + return dtpm->power_limit; + nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(pd->cpus)); rcu_read_lock(); @@ -125,6 +128,9 @@ static int update_pd_power_uw(struct dtpm *dtpm) struct em_perf_state *table; int nr_cpus; + if (!em) + return -EINVAL; + nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(em->cpus)); rcu_read_lock(); -- 2.50.1 (Apple Git-155)