It seems the same patch has been there for a while. http://thread.gmane.org/gmane.linux.kernel/1303115 Regards, Shawn On Sun, Jun 24, 2012 at 12:28:10PM +0200, Javier Martinez Canillas wrote: > On reboot or poweroff (machine_shutdown()) a call to smp_send_stop() is > made (to stop the others CPU's) when CONFIG_SMP=y. > > arch/arm/kernel/process.c: > > void machine_shutdown(void) > { > #ifdef CONFIG_SMP > smp_send_stop(); > #endif > } > > smp_send_stop() calls the function pointer smp_cross_call(), which is set > on the smp_init_cpus() function for OMAP processors. > > arch/arm/mach-omap2/omap-smp.c: > > void __init smp_init_cpus(void) > { > ... > set_smp_cross_call(gic_raise_softirq); > ... > } > > But the ARM setup_arch() function only calls smp_init_cpus() > if CONFIG_SMP=y && is_smp(). > > arm/kernel/setup.c: > > void __init setup_arch(char **cmdline_p) > { > ... > #ifdef CONFIG_SMP > if (is_smp()) > smp_init_cpus(); > #endif > ... > } > > Newer OMAP CPU's are SMP machines so omap2plus_defconfig sets > CONFIG_SMP=y. Unfortunately on an OMAP UP machine is_smp() > returns false and smp_init_cpus() is never called and the > smp_cross_call() function remains NULL. > > If the machine is rebooted or powered off, smp_send_stop() will > be called (since CONFIG_SMP=y) leading to the following error: > > [ 42.815551] Restarting system. > [ 42.819030] Unable to handle kernel NULL pointer dereference at virtual address 00000000 > [ 42.827667] pgd = d7a74000 > [ 42.830566] [00000000] *pgd=96ce7831, *pte=00000000, *ppte=00000000 > [ 42.837249] Internal error: Oops: 80000007 [#1] SMP ARM > [ 42.842773] Modules linked in: > [ 42.846008] CPU: 0 Not tainted (3.5.0-rc3-next-20120622-00002-g62e87ba-dirty #44) > [ 42.854278] PC is at 0x0 > [ 42.856994] LR is at smp_send_stop+0x4c/0xe4 > [ 42.861511] pc : [<00000000>] lr : [<c00183a4>] psr: 60000013 > [ 42.861511] sp : d6c85e70 ip : 00000000 fp : 00000000 > [ 42.873626] r10: 00000000 r9 : d6c84000 r8 : 00000002 > [ 42.879150] r7 : c07235a0 r6 : c06dd2d0 r5 : 000f4241 r4 : d6c85e74 > [ 42.886047] r3 : 00000000 r2 : 00000000 r1 : 00000006 r0 : d6c85e74 > [ 42.892944] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user > [ 42.900482] Control: 10c5387d Table: 97a74019 DAC: 00000015 > [ 42.906555] Process reboot (pid: 1166, stack limit = 0xd6c842f8) > [ 42.912902] Stack: (0xd6c85e70 to 0xd6c86000) > [ 42.917510] 5e60: c07235a0 00000000 00000000 d6c84000 > [ 42.926177] 5e80: 01234567 c00143d0 4321fedc c00511bc d6c85ebc 00000168 00000460 00000000 > [ 42.934814] 5ea0: c1017950 a0000013 c1017900 d8014390 d7ec3858 c0498e48 c1017950 00000000 > [ 42.943481] 5ec0: d6ddde10 d6c85f78 00000003 00000000 d6ddde10 d6c84000 00000000 00000000 > [ 42.952117] 5ee0: 00000002 00000000 00000000 c0088c88 00000002 00000000 00000000 c00f4b90 > [ 42.960784] 5f00: 00000000 d6c85ebc d8014390 d7e311c8 60000013 00000103 00000002 d6c84000 > [ 42.969421] 5f20: c00f3274 d6e00a00 00000001 60000013 d6c84000 00000000 00000000 c00895d4 > [ 42.978057] 5f40: 00000002 d8007c80 d781f000 c00f6150 d8010cc0 c00f3274 d781f000 d6c84000 > [ 42.986694] 5f60: c0013020 d6e00a00 00000001 20000010 0001257c ef000000 00000000 c00895d4 > [ 42.995361] 5f80: 00000002 00000001 00000003 00000000 00000001 00000003 00000000 00000058 > [ 43.003997] 5fa0: c00130c8 c0012f00 00000001 00000003 fee1dead 28121969 01234567 00000002 > [ 43.012634] 5fc0: 00000001 00000003 00000000 00000058 00012584 0001257c 00000001 00000000 > [ 43.021270] 5fe0: 000124bc bec5cc6c 00008f9c 4a2f7c40 20000010 fee1dead 00000000 00000000 > [ 43.029968] [<c00183a4>] (smp_send_stop+0x4c/0xe4) from [<c00143d0>] (machine_restart+0xc/0x4c) > [ 43.039154] [<c00143d0>] (machine_restart+0xc/0x4c) from [<c00511bc>] (sys_reboot+0x144/0x1f0) > [ 43.048278] [<c00511bc>] (sys_reboot+0x144/0x1f0) from [<c0012f00>] (ret_fast_syscall+0x0/0x3c) > [ 43.057464] Code: bad PC value > [ 43.060760] ---[ end trace c3988d1dd0b8f0fb ]--- > > Add a check so smp_cross_call() is only called when there is more than one CPU on-line. > > Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxx> > --- > > Changes since v1: > > - check for cpumask_empty() on arch/arm/kernel/smp.c instead for > is_smp() on arch/arm/kernel/process.c > > arch/arm/kernel/smp.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index 2c7217d..ea73045 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -563,7 +563,8 @@ void smp_send_stop(void) > > cpumask_copy(&mask, cpu_online_mask); > cpumask_clear_cpu(smp_processor_id(), &mask); > - smp_cross_call(&mask, IPI_CPU_STOP); > + if (!cpumask_empty(&mask)) > + smp_cross_call(&mask, IPI_CPU_STOP); > > /* Wait up to one second for other CPUs to stop */ > timeout = USEC_PER_SEC; > -- > 1.7.7.6 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
