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When the kernel is compiled with: CONFIG_HIGH_RES_TIMERS=no CONFIG_HZ_PERIODIC=yes CONFIG_DEBUG_ATOMIC_SLEEP=yes The following WARN appears: WARNING: CPU: 1 PID: 0 at linux/kernel/mutex.c:856 mutex_trylock+0x70/0x1fc() DEBUG_LOCKS_WARN_ON(in_interrupt()) Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.12.0-xilinx-dirty #93 [<c0014a78>] (unwind_backtrace+0x0/0x11c) from [<c0011b6c>] (show_stack+0x10/0x14) [<c0011b6c>] (show_stack+0x10/0x14) from [<c039120c>] (dump_stack+0x7c/0xc0) [<c039120c>] (dump_stack+0x7c/0xc0) from [<c001fda4>] (warn_slowpath_common+0x60/0x84) [<c001fda4>] (warn_slowpath_common+0x60/0x84) from [<c001fe48>] (warn_slowpath_fmt+0x2c/0x3c) [<c001fe48>] (warn_slowpath_fmt+0x2c/0x3c) from [<c0392658>] (mutex_trylock+0x70/0x1fc) [<c0392658>] (mutex_trylock+0x70/0x1fc) from [<c02dfc08>] (clk_prepare_lock+0xc/0xe4) [<c02dfc08>] (clk_prepare_lock+0xc/0xe4) from [<c02e099c>] (clk_get_rate+0xc/0x44) [<c02e099c>] (clk_get_rate+0xc/0x44) from [<c02d0394>] (ttc_set_mode+0x34/0x78) [<c02d0394>] (ttc_set_mode+0x34/0x78) from [<c005f794>] (clockevents_set_mode+0x28/0x5c) [<c005f794>] (clockevents_set_mode+0x28/0x5c) from [<c00607fc>] (tick_broadcast_on_off+0x190/0x1c0) [<c00607fc>] (tick_broadcast_on_off+0x190/0x1c0) from [<c005f168>] (clockevents_notify+0x58/0x1ac) [<c005f168>] (clockevents_notify+0x58/0x1ac) from [<c02b99dc>] (cpuidle_setup_broadcast_timer+0x20/0x24) [<c02b99dc>] (cpuidle_setup_broadcast_timer+0x20/0x24) from [<c006cd04>] (generic_smp_call_function_single_interrupt+0) [<c006cd04>] (generic_smp_call_function_single_interrupt+0xe0/0x130) from [<c00138c8>] (handle_IPI+0x88/0x118) [<c00138c8>] (handle_IPI+0x88/0x118) from [<c0008504>] (gic_handle_irq+0x58/0x60) [<c0008504>] (gic_handle_irq+0x58/0x60) from [<c0012644>] (__irq_svc+0x44/0x78) Exception stack(0xef099fa0 to 0xef099fe8) 9fa0: 00000001 ef092100 00000000 ef092100 ef098000 00000015 c0399f2c c0579d74 9fc0: 0000406a 413fc090 00000000 00000000 00000000 ef099fe8 c00666ec c000f46c 9fe0: 20000113 ffffffff [<c0012644>] (__irq_svc+0x44/0x78) from [<c000f46c>] (arch_cpu_idle+0x34/0x3c) [<c000f46c>] (arch_cpu_idle+0x34/0x3c) from [<c0053980>] (cpu_startup_entry+0xa8/0x10c) [<c0053980>] (cpu_startup_entry+0xa8/0x10c) from [<000085a4>] (0x85a4) We are in an interrupt context (IPI) and we are calling clk_get_rate in the set_mode function which in turn ends up by getting a mutex... Even if that does not hang, it is a potential kernel deadlock. It is not allowed to call clk_get_rate() from interrupt context. To avoid such calls the timer input frequency is stored in the driver's data struct which makes it accessible to the driver in any context. [dlezcano] completed the changelog with the WARN trace and added a more detailed description. Tested on zync zc702. Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> |
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| .. | ||
| acpi_pm.c | ||
| arm_arch_timer.c | ||
| arm_global_timer.c | ||
| bcm2835_timer.c | ||
| bcm_kona_timer.c | ||
| cadence_ttc_timer.c | ||
| clksrc-dbx500-prcmu.c | ||
| clksrc-of.c | ||
| cs5535-clockevt.c | ||
| cyclone.c | ||
| dummy_timer.c | ||
| dw_apb_timer_of.c | ||
| dw_apb_timer.c | ||
| em_sti.c | ||
| exynos_mct.c | ||
| i8253.c | ||
| Kconfig | ||
| Makefile | ||
| metag_generic.c | ||
| mmio.c | ||
| moxart_timer.c | ||
| mxs_timer.c | ||
| nomadik-mtu.c | ||
| samsung_pwm_timer.c | ||
| scx200_hrt.c | ||
| sh_cmt.c | ||
| sh_mtu2.c | ||
| sh_tmu.c | ||
| sun4i_timer.c | ||
| tcb_clksrc.c | ||
| tegra20_timer.c | ||
| time-armada-370-xp.c | ||
| time-efm32.c | ||
| time-orion.c | ||
| timer-marco.c | ||
| timer-prima2.c | ||
| vf_pit_timer.c | ||
| vt8500_timer.c | ||
| zevio-timer.c | ||