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UPSTREAM: MIPS: smp-cps: Avoid BUG() when offlining pre-r6 CPUs

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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 <matt.redfearn@imgtec.com>
Cc: Qais Yousef <qsyousef@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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 <ralf@linux-mips.org>
(cherry picked from commit 6ca8ac773e97e2dfa5734ae435c40e672dd19ac4)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Matt Redfearn 2016-09-22 11:59:47 +01:00 • committed by Greg Kroah-Hartman
parent 63a30ac54e
commit b4af2637b6
1 changed files with 1 additions and 1 deletions
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2
arch/mips/kernel/smp-cps.c
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@ -504,7 +504,7 @@ 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;