From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: [PATCH v1] soc/tegra: pmc: Drop locking from tegra_powergate_is_powered() Date: Sun, 21 Oct 2018 21:36:14 +0300 Message-ID: <20181021183614.454-1-digetx@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Thierry Reding , Jonathan Hunter Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-tegra@vger.kernel.org This fixes splats like the one below if CONFIG_DEBUG_ATOMIC_SLEEP=y and machine (Tegra30) booted with SMP=n or all secondary CPU's are put offline. Locking isn't needed because it protects atomic operation. # echo 0 | tee /sys/devices/system/cpu/cpu[1-3]/online BUG: sleeping function called from invalid context at kernel/locking/mutex.c:254 in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0 CPU: 0 PID: 0 Comm: swapper/0 Tainted: G C 4.18.0-next-20180821-00180-gc3ebb6544e44-dirty #823 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x20/0x24) [] (show_stack) from [] (dump_stack+0x94/0xa8) [] (dump_stack) from [] (___might_sleep+0x13c/0x174) [] (___might_sleep) from [] (__might_sleep+0x70/0xa8) [] (__might_sleep) from [] (mutex_lock+0x2c/0x70) [] (mutex_lock) from [] (tegra_powergate_is_powered+0x44/0xa8) [] (tegra_powergate_is_powered) from [] (tegra30_cpu_rail_off_ready+0x30/0x74) [] (tegra30_cpu_rail_off_ready) from [] (tegra30_idle_lp2+0xa0/0x108) [] (tegra30_idle_lp2) from [] (cpuidle_enter_state+0x140/0x540) [] (cpuidle_enter_state) from [] (cpuidle_enter+0x40/0x4c) [] (cpuidle_enter) from [] (call_cpuidle+0x30/0x48) [] (call_cpuidle) from [] (do_idle+0x238/0x28c) [] (do_idle) from [] (cpu_startup_entry+0x28/0x2c) [] (cpu_startup_entry) from [] (rest_init+0xd8/0xdc) [] (rest_init) from [] (start_kernel+0x41c/0x430) Signed-off-by: Dmitry Osipenko --- drivers/soc/tegra/pmc.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c index 1fa840e3d930..1714cd818d69 100644 --- a/drivers/soc/tegra/pmc.c +++ b/drivers/soc/tegra/pmc.c @@ -543,9 +543,7 @@ int tegra_powergate_is_powered(unsigned int id) if (!tegra_powergate_is_valid(id)) return -EINVAL; - mutex_lock(&pmc->powergates_lock); status = tegra_powergate_state(id); - mutex_unlock(&pmc->powergates_lock); return status; } -- 2.19.0