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MIPS: Loongson-3: Fix SMP_ASK_C0COUNT IPI handler

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When Core-0 handle SMP_ASK_C0COUNT IPI, we should make other cores to
see the result as soon as possible (especially when Store-Fill-Buffer
is enabled). Otherwise, C0_Count syncronization makes no sense.

BTW, array is more suitable than per-cpu variable for syncronization,
and there is a corner case should be avoid: C0_Count of Core-0 can be
really 0.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org>
Patchwork: https://patchwork.linux-mips.org/patch/12160/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Huacai Chen 2016-01-21 21:09:49 +08:00 committed by Ralf Baechle
parent 5188129b8c
commit 5754843225
1 changed files with 13 additions and 7 deletions
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20
arch/mips/loongson64/loongson-3/smp.c
View File

@ -30,13 +30,13 @@
#include "smp.h"
DEFINE_PER_CPU(int, cpu_state);
DEFINE_PER_CPU(uint32_t, core0_c0count);
static void *ipi_set0_regs[16];
static void *ipi_clear0_regs[16];
static void *ipi_status0_regs[16];
static void *ipi_en0_regs[16];
static void *ipi_mailbox_buf[16];
static uint32_t core0_c0count[NR_CPUS];
/* read a 32bit value from ipi register */
#define loongson3_ipi_read32(addr) readl(addr)
@ -275,12 +275,14 @@ void loongson3_ipi_interrupt(struct pt_regs *regs)
if (action & SMP_ASK_C0COUNT) {
BUG_ON(cpu != 0);
c0count = read_c0_count();
for (i = 1; i < num_possible_cpus(); i++)
per_cpu(core0_c0count, i) = c0count;
c0count = c0count ? c0count : 1;
for (i = 1; i < nr_cpu_ids; i++)
core0_c0count[i] = c0count;
__wbflush(); /* Let others see the result ASAP */
}
}
#define MAX_LOOPS 1111
#define MAX_LOOPS 800
/*
* SMP init and finish on secondary CPUs
*/
@ -305,16 +307,20 @@ static void loongson3_init_secondary(void)
cpu_logical_map(cpu) / loongson_sysconf.cores_per_package;
i = 0;
__this_cpu_write(core0_c0count, 0);
core0_c0count[cpu] = 0;
loongson3_send_ipi_single(0, SMP_ASK_C0COUNT);
while (!__this_cpu_read(core0_c0count)) {
while (!core0_c0count[cpu]) {
i++;
cpu_relax();
}
if (i > MAX_LOOPS)
i = MAX_LOOPS;
initcount = __this_cpu_read(core0_c0count) + i;
if (cpu_data[cpu].package)
initcount = core0_c0count[cpu] + i;
else /* Local access is faster for loops */
initcount = core0_c0count[cpu] + i/2;
write_c0_count(initcount);
}