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perf_counter: abstract wakeup flag setting in core to fix powerpc build

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Impact: build fix for powerpc

Commit bd753921015e7905 ("perf_counter: software counter event
infrastructure") introduced a use of TIF_PERF_COUNTERS into the core
perfcounter code.  This breaks the build on powerpc because we use
a flag in a per-cpu area to signal wakeups on powerpc rather than
a thread_info flag, because the thread_info flags have to be
manipulated with atomic operations and are thus slower than per-cpu
flags.

This fixes the by changing the core to use an abstracted
set_perf_counter_pending() function, which is defined on x86 to set
the TIF_PERF_COUNTERS flag and on powerpc to set the per-cpu flag
(paca->perf_counter_pending).  It changes the previous powerpc
definition of set_perf_counter_pending to not take an argument and
adds a clear_perf_counter_pending, so as to simplify the definition
on x86.

On x86, set_perf_counter_pending() is defined as a macro.  Defining
it as a static inline in arch/x86/include/asm/perf_counters.h causes
compile failures because <asm/perf_counters.h> gets included early in
<linux/sched.h>, and the definitions of set_tsk_thread_flag etc. are
therefore not available in <asm/perf_counters.h>.  (On powerpc this
problem is avoided by defining set_perf_counter_pending etc. in
<asm/hw_irq.h>.)

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras 2009-03-16 21:00:00 +11:00 • committed by Ingo Molnar
parent 7bb497bd88
commit b6c5a71da1
5 changed files with 19 additions and 14 deletions
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14
arch/powerpc/include/asm/hw_irq.h
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@ -142,10 +142,17 @@ static inline unsigned long get_perf_counter_pending(void)
return x;
}
static inline void set_perf_counter_pending(int x)
static inline void set_perf_counter_pending(void)
{
asm volatile("stb %0,%1(13)" : :
"r" (x),
"r" (1),
"i" (offsetof(struct paca_struct, perf_counter_pending)));
}
static inline void clear_perf_counter_pending(void)
{
asm volatile("stb %0,%1(13)" : :
"r" (0),
"i" (offsetof(struct paca_struct, perf_counter_pending)));
}
@ -158,7 +165,8 @@ static inline unsigned long get_perf_counter_pending(void)
return 0;
}
static inline void set_perf_counter_pending(int x) {}
static inline void set_perf_counter_pending(void) {}
static inline void clear_perf_counter_pending(void) {}
static inline void perf_counter_do_pending(void) {}
#endif /* CONFIG_PERF_COUNTERS */