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| author | Henrik Austad <haustad@cisco.com> | 2013-03-26 08:16:42 +0100 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2013-03-26 18:52:16 +0100 |
| commit | 39e8202bb3b83a826e5825b1a07bbbf30ae9a140 (patch) | |
| tree | a4c2a4fd3198fd326836d61db3f39a49f5b722de /arch/tile | |
| parent | arch: remove KCORE_ELF again [tile] (diff) | |
| download | linux-39e8202bb3b83a826e5825b1a07bbbf30ae9a140.tar.xz linux-39e8202bb3b83a826e5825b1a07bbbf30ae9a140.zip | |
tile: ns2cycles should use __raw_get_cpu_var
ns2cycles use per_cpu variables, and will, eventually, find its way into
smp_processor_id(). This is not safe in a preemptible kernel;
preemption should ideally be disabled.
BUG: using smp_processor_id() in preemptible [00000000] code:
systemd-modules/367
caller is ns2cycles+0x40/0xb8
Starting stack dump of tid 367, pid 367 (systemd-modules) on cpu 2 at
cycle 20969956421
frame 0: 0xfffffff70004b860 dump_stack+0x0/0x20 (sp 0xfffffe407993fa90)
frame 1: 0xfffffff7006abc28 debug_smp_processor_id+0x1a8/0x1e0 (sp
0xfffffe407993fa90)
frame 2: 0xfffffff7004d7b40 ns2cycles+0x40/0xb8 (sp 0xfffffe407993fab8)
frame 3: 0xfffffff7004dc578 __ndelay+0x38/0x80 (sp 0xfffffe407993fae0)
However, in this case:
- the frequency is the same accross all cores
- we use the data read-only
- we do not scale the frequency
Which means that we can use the __raw_get_cpu_var instead.
Signed-off-by: Henrik Austad <haustad@cisco.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile')
| -rw-r--r-- | arch/tile/kernel/time.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/tile/kernel/time.c b/arch/tile/kernel/time.c index f6f50f2a5e37..5ac397ec6986 100644 --- a/arch/tile/kernel/time.c +++ b/arch/tile/kernel/time.c @@ -230,6 +230,10 @@ int setup_profiling_timer(unsigned int multiplier) */ cycles_t ns2cycles(unsigned long nsecs) { - struct clock_event_device *dev = &__get_cpu_var(tile_timer); + /* + * We do not have to disable preemption here as each core has the same + * clock frequency. + */ + struct clock_event_device *dev = &__raw_get_cpu_var(tile_timer); return ((u64)nsecs * dev->mult) >> dev->shift; } |