On 10/24/18 1:20 PM, Jon Hunter wrote: > > On 21/10/2018 19:36, Dmitry Osipenko wrote: >> 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) >> [<c01134f4>] (unwind_backtrace) from [<c010db2c>] (show_stack+0x20/0x24) >> [<c010db2c>] (show_stack) from [<c0bd0f3c>] (dump_stack+0x94/0xa8) >> [<c0bd0f3c>] (dump_stack) from [<c0151df8>] (___might_sleep+0x13c/0x174) >> [<c0151df8>] (___might_sleep) from [<c0151ea0>] (__might_sleep+0x70/0xa8) >> [<c0151ea0>] (__might_sleep) from [<c0bec2b8>] (mutex_lock+0x2c/0x70) >> [<c0bec2b8>] (mutex_lock) from [<c0589844>] (tegra_powergate_is_powered+0x44/0xa8) >> [<c0589844>] (tegra_powergate_is_powered) from [<c0581a60>] (tegra30_cpu_rail_off_ready+0x30/0x74) >> [<c0581a60>] (tegra30_cpu_rail_off_ready) from [<c0122244>] (tegra30_idle_lp2+0xa0/0x108) >> [<c0122244>] (tegra30_idle_lp2) from [<c0853438>] (cpuidle_enter_state+0x140/0x540) >> [<c0853438>] (cpuidle_enter_state) from [<c08538a4>] (cpuidle_enter+0x40/0x4c) >> [<c08538a4>] (cpuidle_enter) from [<c01595e0>] (call_cpuidle+0x30/0x48) >> [<c01595e0>] (call_cpuidle) from [<c01599f8>] (do_idle+0x238/0x28c) >> [<c01599f8>] (do_idle) from [<c0159d28>] (cpu_startup_entry+0x28/0x2c) >> [<c0159d28>] (cpu_startup_entry) from [<c0be76c8>] (rest_init+0xd8/0xdc) >> [<c0be76c8>] (rest_init) from [<c1200f50>] (start_kernel+0x41c/0x430) >> >> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> >> --- >> 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; > > Can we just ... > > return tegra_powergate_state(id); We can, but it is not necessary. Feel free to adjust the code as you wish while applying ;) I deliberately left the 'status' variable because I think that makes code a bit more expressive.
