diff options
| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2011-06-16 15:36:38 -0400 |
|---|---|---|
| committer | Dave Jones <davej@redhat.com> | 2011-06-16 16:31:12 -0400 |
| commit | 46a310b80bc2c9ccc019649c9da91194cbc10944 (patch) | |
| tree | ee83955c171f7fd491bf06d7c9592b589ae0c7d0 /drivers | |
| parent | ada9c93312f7ec49514c68c211595ce2601cebae (diff) | |
| download | linux-46a310b80bc2c9ccc019649c9da91194cbc10944.tar.bz2 | |
[CPUFREQ] Don't set stat->last_index to -1 if the pol->cur has incorrect value.
If the driver submitted an non-existing pol>cur value (say it
used the default initialized value of zero), when the cpufreq
stats tries to setup its initial values it incorrectly sets
stat->last_index to -1 (or 0xfffff...). And cpufreq_stats_update
tries to update at that index location and fails.
This can be caused by:
stat->last_index = freq_table_get_index(stat, policy->cur);
not finding the appropiate frequency in the table (b/c the policy->cur
is wrong) and we end up crashing. The fix however is
concentrated in the 'cpufreq_stats_update' as the last_index
(and old_index) are updated there. Which means it can reset
the last_index to -1 again and on the next iteration cause a crash.
Without this patch, the following crash is observed:
powernow-k8: Found 1 AMD Athlon(tm) 64 Processor 3700+ (1 cpu cores) (version 2.20.00)
powernow-k8: fid 0x2 (1000 MHz), vid 0x12
powernow-k8: fid 0xa (1800 MHz), vid 0xa
powernow-k8: fid 0xc (2000 MHz), vid 0x8
powernow-k8: fid 0xe (2200 MHz), vid 0x8
Marking TSC unstable due to cpufreq changes
powernow-k8: fid trans failed, fid 0x2, curr 0x0
BUG: unable to handle kernel paging request at ffff880807e07b78
IP: [<ffffffff81479163>] cpufreq_stats_update+0x46/0x5b
.. snip..
Pid: 1, comm: swapper Not tainted 3.0.0-rc2 #45 MICRO-STAR INTERNATIONAL CO., LTD MS-7094/MS-7094
..snip..
Call Trace:
[<ffffffff81479248>] cpufreq_stat_notifier_trans+0x48/0x7c
[<ffffffff81095d68>] notifier_call_chain+0x32/0x5e
[<ffffffff81095e6b>] __srcu_notifier_call_chain+0x47/0x63
[<ffffffff81095e96>] srcu_notifier_call_chain+0xf/0x11
[<ffffffff81477e7a>] cpufreq_notify_transition+0x111/0x134
[<ffffffff8147b0d4>] powernowk8_target+0x53b/0x617
[<ffffffff8147723a>] __cpufreq_driver_target+0x2e/0x30
[<ffffffff8147a127>] cpufreq_governor_dbs+0x339/0x356
[<ffffffff81477394>] __cpufreq_governor+0xa8/0xe9
[<ffffffff81477525>] __cpufreq_set_policy+0x132/0x13e
[<ffffffff8147848d>] cpufreq_add_dev_interface+0x272/0x28c
Reported-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Tested-by: Tobias Diedrich <ranma+xen@tdiedrich.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Dave Jones <davej@redhat.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/cpufreq/cpufreq_stats.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c index 853f92d23ddb..faf7c5217848 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -298,11 +298,13 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb, old_index = stat->last_index; new_index = freq_table_get_index(stat, freq->new); - cpufreq_stats_update(freq->cpu); - if (old_index == new_index) + /* We can't do stat->time_in_state[-1]= .. */ + if (old_index == -1 || new_index == -1) return 0; - if (old_index == -1 || new_index == -1) + cpufreq_stats_update(freq->cpu); + + if (old_index == new_index) return 0; spin_lock(&cpufreq_stats_lock); |