Patch "MIPS: Call dump_stack() from show_regs()" has been added to the 4.9-stable tree

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This is a note to let you know that I've just added the patch titled

    MIPS: Call dump_stack() from show_regs()

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-call-dump_stack-from-show_regs.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 5a267832c2ec47b2dad0fdb291a96bb5b8869315 Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@xxxxxxxx>
Date: Fri, 22 Jun 2018 10:55:45 -0700
Subject: MIPS: Call dump_stack() from show_regs()

From: Paul Burton <paul.burton@xxxxxxxx>

commit 5a267832c2ec47b2dad0fdb291a96bb5b8869315 upstream.

The generic nmi_cpu_backtrace() function calls show_regs() when a struct
pt_regs is available, and dump_stack() otherwise. If we were to make use
of the generic nmi_cpu_backtrace() with MIPS' current implementation of
show_regs() this would mean that we see only register data with no
accompanying stack information, in contrast with our current
implementation which calls dump_stack() regardless of whether register
state is available.

In preparation for making use of the generic nmi_cpu_backtrace() to
implement arch_trigger_cpumask_backtrace(), have our implementation of
show_regs() call dump_stack() and drop the explicit dump_stack() call in
arch_dump_stack() which is invoked by arch_trigger_cpumask_backtrace().

This will allow the output we produce to remain the same after a later
patch switches to using nmi_cpu_backtrace(). It may mean that we produce
extra stack output in other uses of show_regs(), but this:

  1) Seems harmless.
  2) Is good for consistency between arch_trigger_cpumask_backtrace()
     and other users of show_regs().
  3) Matches the behaviour of the ARM & PowerPC architectures.

Marked for stable back to v4.9 as a prerequisite of the following patch
"MIPS: Call dump_stack() from show_regs()".

Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Patchwork: https://patchwork.linux-mips.org/patch/19596/
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Huacai Chen <chenhc@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # v4.9+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/mips/kernel/process.c |    4 ++--
 arch/mips/kernel/traps.c   |    1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -641,8 +641,8 @@ static void arch_dump_stack(void *info)
 
 	if (regs)
 		show_regs(regs);
-
-	dump_stack();
+	else
+		dump_stack();
 }
 
 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -351,6 +351,7 @@ static void __show_regs(const struct pt_
 void show_regs(struct pt_regs *regs)
 {
 	__show_regs((struct pt_regs *)regs);
+	dump_stack();
 }
 
 void show_registers(struct pt_regs *regs)


Patches currently in stable-queue which might be from paul.burton@xxxxxxxx are

queue-4.9/mips-call-dump_stack-from-show_regs.patch
queue-4.9/mips-fix-ioremap-ram-check.patch
queue-4.9/mips-use-async-ipis-for-arch_trigger_cpumask_backtrace.patch




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