[Powertop] [PATCH] Fix crash on Linux ARM hosts

* [Powertop] [PATCH] Fix crash on Linux ARM hosts
@ 2012-07-12 18:41 Stefan Weil
  0 siblings, 0 replies; 6+ messages in thread
From: Stefan Weil @ 2012-07-12 18:41 UTC (permalink / raw)
  To: powertop

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/proc/cpuinfo on ARM hosts is different and resulted
in a call of handle_one_cpu() with number == -1
which finally raised a SIGSEGV crash (noticed on
Debian Wheezy for ARM).

Fix this by testing the value of "number".

After number was used, it is now reset to -1 just to make
sure that the new test also works for a potential 2nd cpu
with unexpected information in /proc/cpuinfo.

Signed-off-by: Stefan Weil <sw(a)weilnetz.de>
---

Please note that even with this patch, powertop on ARM will
only work partially: handle_one_cpu() is never called,
so there is no cpu information.

For ARM hosts with a single core cpu (the most common case),
using a case insensitive compare for 'processor' would work.

This is my /proc/cpuinfo:

Processor	: ARMv6-compatible processor rev 7 (v6l)
BogoMIPS	: 697.95
Features	: swp half thumb fastmult vfp edsp java tls 
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0
CPU part	: 0xb76
CPU revision	: 7

Hardware	: BCM2708
Revision	: 0002
Serial		: 00000000e16a63c5

For multicore cpus, a better 2nd patch is needed.
If anybody has a /proc/cpuinfo of that kind, please tell me
the format - otherwise I'll have to look in the Linux source.

Regards,
Stefan Weil

 src/cpu/cpu.cpp |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/cpu/cpu.cpp b/src/cpu/cpu.cpp
index 4096835..d08bdcd 100644
--- a/src/cpu/cpu.cpp
+++ b/src/cpu/cpu.cpp
@@ -271,8 +271,11 @@ void enumerate_cpus(void)
 			}
 		}
 		if (strncasecmp(line, "bogomips\t", 9) == 0) {
-			handle_one_cpu(number, vendor, family, model);
-			set_max_cpu(number);
+			if (number >= 0) {
+				handle_one_cpu(number, vendor, family, model);
+				set_max_cpu(number);
+				number = -1;
+			}
 		}
 	}
 
-- 
1.7.10


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