We're using kernel 2.6.33.5 with corresponding 2.6.33.5-rt25 patches. __setup_irq in request_kernel/irq/manage.c contains a block guarded by a raw spinlock, with a preceding comment noting "The following block of code has to be executed atomically". Why is this so? I ask because during RTC setup, this atomic region is causing calls to twl4030_sih_* functions to fail on my BeagleBoard platform (see stack trace below from a previous thread.). As Gowrishankar noted in the previous thread, those routines use (non-raw) spinlocking. As Thomas noted, they also call queue_work, which in turn relies on non-raw spinlocking, so just patching up the twl4030_sih_* functions to use raw calls doesn't solve the problem. I'm presently experimenting with: a) pulling the calls to__irq_set_trigger and desc->chip->startup to a spot after the call to raw_spin_unlock_irqrestore, or b) making the atomic region use non-raw locking. However, I'm not really sure what the consequences of either approach are likely to be. I'd be grateful for any thoughts and/or guidance that will keep me from wasting time and/or breaking things in subtle and confusing ways. Thanks in advance, Jeremy On Tue, Jul 20, 2010 at 3:26 PM, Jeremy Brown <jhbrown@xxxxxxxxxxxxxxxx> wrote: > We're trying to get a PREEMPT_RT kernel running on a BeagleBoard C4 > (OMAP3 Arm architecture). We're using kernel version 2.6.33, with > patches from > patch-2.6.33.6-rt26.gz > > On boot, we start seeing messages of this form: > > ---- > [ 4528.227294] BUG: sleeping function called from invalid context at > kernel/rtmutex.c:684 > [ 4528.227294] pcnt: 1 0 in_atomic(): 1, irqs_disabled(): 128, pid: > 223, name: modprobe > [ 4528.227355] [<c0044490>] (unwind_backtrace+0x0/0xe8) from > [<c04cb4e4>] (rt_spin_lock+0x30/0x5c) > [ 4528.227386] [<c04cb4e4>] (rt_spin_lock+0x30/0x5c) from [<c032e3b0>] > (twl4030_sih_set_type+0x3c/0xac) > [ 4528.227416] [<c032e3b0>] (twl4030_sih_set_type+0x3c/0xac) from > [<c00aa944>] (__irq_set_trigger+0x34/0x88) > [ 4528.227447] [<c00aa944>] (__irq_set_trigger+0x34/0x88) from > [<c00ab2ec>] (__setup_irq+0x34c/0x3c0) > [ 4528.227478] [<c00ab2ec>] (__setup_irq+0x34c/0x3c0) from > [<c00ab430>] (request_threaded_irq+0xd0/0x148) > [ 4528.227508] [<c00ab430>] (request_threaded_irq+0xd0/0x148) from > [<bf021770>] (twl_rtc_probe+0x104/0x1fc [rtc_twl]) > [ 4528.227539] [<bf021770>] (twl_rtc_probe+0x104/0x1fc [rtc_twl]) from > [<c0324e2c>] (platform_drv_probe+0x18/0x1c) > [ 4528.227569] [<c0324e2c>] (platform_drv_probe+0x18/0x1c) from > [<c0323eec>] (driver_probe_device+0x98/0x194) > [ 4528.227600] [<c0323eec>] (driver_probe_device+0x98/0x194) from > [<c0324074>] (__driver_attach+0x8c/0x90) > [ 4528.227600] [<c0324074>] (__driver_attach+0x8c/0x90) from > [<c0323744>] (bus_for_each_dev+0x60/0x8c) > [ 4528.227630] [<c0323744>] (bus_for_each_dev+0x60/0x8c) from > [<c0323014>] (bus_add_driver+0xa0/0x240) > [ 4528.227661] [<c0323014>] (bus_add_driver+0xa0/0x240) from > [<c0324324>] (driver_register+0x78/0x13c) > [ 4528.227661] [<c0324324>] (driver_register+0x78/0x13c) from > [<c003e3c0>] (do_one_initcall+0x30/0x1c0) > [ 4528.227691] [<c003e3c0>] (do_one_initcall+0x30/0x1c0) from > [<c0097e40>] (sys_init_module+0xc4/0x1f8) > [ 4528.227722] [<c0097e40>] (sys_init_module+0xc4/0x1f8) from > [<c003ea60>] (ret_fast_syscall+0x0/0x2c) -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
