On Tue, Dec 05, 2017 at 10:28:22PM +0000, James Hogan wrote:
Since commit 68923cdc2eb3 ("MIPS: CM: Add cluster & block args to mips_cm_lock_other()"), mips_smp_send_ipi_mask() has used mips_cm_lock_other_cpu() with each CPU number, rather than mips_cm_lock_other() with the first VPE in each core. Prior to r6, multicore multithreaded systems such as dual-core dual-thread interAptivs with CPU Idle enabled (e.g. MIPS Creator Ci40) results in mips_cm_lock_other() repeatedly hitting WARN_ON(vp != 0).
There doesn't appear to be anything fundamentally wrong about passing a non-zero VP/VPE number, even if it is a core's region that is locked into the other region before r6, so remove that particular WARN_ON().
Fixes: 68923cdc2eb3 ("MIPS: CM: Add cluster & block args to mips_cm_lock_other()") Signed-off-by: James Hogan jhogan@kernel.org Reviewed-by: Paul Burton paul.burton@mips.com Cc: Ralf Baechle ralf@linux-mips.org Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # 4.14+
arch/mips/kernel/mips-cm.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/arch/mips/kernel/mips-cm.c b/arch/mips/kernel/mips-cm.c index dd5567b1e305..8f5bd04f320a 100644 --- a/arch/mips/kernel/mips-cm.c +++ b/arch/mips/kernel/mips-cm.c @@ -292,7 +292,6 @@ void mips_cm_lock_other(unsigned int cluster, unsigned int core, *this_cpu_ptr(&cm_core_lock_flags)); } else { WARN_ON(cluster != 0);
WARN_ON(vp != 0);
I think the reason is that for a while the combination of SMP/CMP with MT was at the bottom of priorities and nobody really cared about it so a WARN_ON was thrown in. Which in this case might well itself be a bug!
Ralf