[PATCH 9/9] ARM: tegra: fix sleeping while atomic in CPU idle
From: mirq-linux@rere.qmqm.pl (Michał Mirosław)
Date: 2017-07-20 16:28:52
Also in:
linux-tegra
On Thu, Jul 20, 2017 at 01:45:12PM +0100, Jon Hunter wrote:
quoted hunk ↗ jump to hunk
On 20/07/17 01:29, Micha? Miros?aw wrote:quoted
This removes unnecessary lock causing following BUG splat: BUG: sleeping function called from invalid context at /linux/kernel/locking/mutex.c:747 in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0 no locks held by swapper/0/0. CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 4.13.0-rc1mq-00016-gbf3f627c6b2b #1 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) [<b0110a14>] (unwind_backtrace) from [<b010c710>] (show_stack+0x18/0x1c) [<b010c710>] (show_stack) from [<b068ada8>] (dump_stack+0x84/0x98) [<b068ada8>] (dump_stack) from [<b014ff54>] (___might_sleep+0x158/0x17c) [<b014ff54>] (___might_sleep) from [<b06a15c4>] (__mutex_lock+0x34/0x9a0) [<b06a15c4>] (__mutex_lock) from [<b06a30dc>] (mutex_lock_nested+0x24/0x2c) [<b06a30dc>] (mutex_lock_nested) from [<b041f6d8>] (tegra_powergate_is_powered+0x40/0xa4) [<b041f6d8>] (tegra_powergate_is_powered) from [<b04197e8>] (tegra30_cpu_rail_off_ready+0x28/0x6c) [<b04197e8>] (tegra30_cpu_rail_off_ready) from [<b011c73c>] (tegra30_idle_lp2+0x70/0x114) [<b011c73c>] (tegra30_idle_lp2) from [<b0516080>] (cpuidle_enter_state+0x12c/0x47c) [<b0516080>] (cpuidle_enter_state) from [<b0163394>] (do_idle+0x1b4/0x204) [<b0163394>] (do_idle) from [<b016368c>] (cpu_startup_entry+0x20/0x24) [<b016368c>] (cpu_startup_entry) from [<b0900dd8>] (start_kernel+0x39c/0x3a8) Signed-off-by: Micha? Miros?aw <mirq-linux@rere.qmqm.pl> --- 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 e233dd5dcab3..3e6ec9fdba41 100644 --- a/drivers/soc/tegra/pmc.c +++ b/drivers/soc/tegra/pmc.c@@ -526,9 +526,7 @@ 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; }Thanks for the fix. However, I would prefer that we fix this the following way ...diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c index a2d163f759b4..546d2b121c39 100644 --- a/drivers/clk/tegra/clk-tegra30.c +++ b/drivers/clk/tegra/clk-tegra30.c@@ -1152,9 +1152,9 @@ static bool tegra30_cpu_rail_off_ready(void) cpu_rst_status = readl(clk_base + TEGRA30_CLK_RST_CONTROLLER_CPU_CMPLX_STATUS); - cpu_pwr_status = tegra_powergate_is_powered(TEGRA_POWERGATE_CPU1) || - tegra_powergate_is_powered(TEGRA_POWERGATE_CPU2) || - tegra_powergate_is_powered(TEGRA_POWERGATE_CPU3); + cpu_pwr_status = tegra_pmc_cpu_is_powered(1) || + tegra_pmc_cpu_is_powered(2) || + tegra_pmc_cpu_is_powered(3); if (((cpu_rst_status & 0xE) != 0xE) || cpu_pwr_status) return false;diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c index e233dd5dcab3..f61371ea3fe0 100644 --- a/drivers/soc/tegra/pmc.c +++ b/drivers/soc/tegra/pmc.c@@ -605,7 +605,7 @@ bool tegra_pmc_cpu_is_powered(unsigned int cpuid) if (id < 0) return false; - return tegra_powergate_is_powered(id); + return tegra_powergate_state(id); }Could you try the above and make sure that this works?
Something ate TABs in your patch, but yes, it works.
I would prefer to leave the mutex in tegra_powergate_is_powered() so it could be used by any driver. Or maybe we could even get rid of tegra_powergate_is_powered() if we don't really need it.
This mutex does not protect anything here, though - there is only one register read inside the locked section, and after unlock other CPU might change it before the read value gets returned. Code size-wise it would be better to remove tegra_pmc_cpu_is_powered() instead. Best Regards, Micha??Miros?aw