From 6ca8ac773e97e2dfa5734ae435c40e672dd19ac4 Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Thu, 22 Sep 2016 11:59:47 +0100 Subject: [PATCH] MIPS: smp-cps: Avoid BUG() when offlining pre-r6 CPUs Commit 0d2808f338c7 ("MIPS: smp-cps: Add support for CPU hotplug of MIPSr6 processors") added a call to mips_cm_lock_other in order to lock the CPC in CPUs containing a version 3 or higher Coherence Manager, which use the general CM core other register, where previous CMs had a dedicated core other register for the CPC. A kernel BUG() is triggered, however, if mips_cm_lock_other is called with a VP other than 0 on a CPU with CM < 3, a condition introduced by 0d2808f338c7. Avoid the BUG() by always locking VP0 when locking the CPC, since the required register, cpc_stat_conf, is shared by all vps in a core. Fixes: 0d2808f338c7 ("MIPS: smp-cps: Add support for CPU hotplug...) Signed-off-by: Matt Redfearn Cc: Qais Yousef Cc: Masahiro Yamada Cc: James Hogan Cc: Paul Burton Cc: Andrew Morton Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/14297/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/smp-cps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c index e9d9fc6c754c..6183ad84cc73 100644 --- a/arch/mips/kernel/smp-cps.c +++ b/arch/mips/kernel/smp-cps.c @@ -513,7 +513,7 @@ static void cps_cpu_die(unsigned int cpu) * in which case the CPC will refuse to power down the core. */ do { - mips_cm_lock_other(core, vpe_id); + mips_cm_lock_other(core, 0); mips_cpc_lock_other(core); stat = read_cpc_co_stat_conf(); stat &= CPC_Cx_STAT_CONF_SEQSTATE_MSK; -- 2.20.1