4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Huacai Chen <che...@lemote.com> commit 5754843225f78ac7cbe142a6899890a9733a5a5d upstream. 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 <che...@lemote.com> Cc: Aurelien Jarno <aurel...@aurel32.net> Cc: Steven J. Hill <steven.h...@imgtec.com> Cc: Fuxin Zhang <zhan...@lemote.com> Cc: Zhangjin Wu <wuzhang...@gmail.com> Cc: Huacai Chen <che...@lemote.com> Cc: linux-m...@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/12160/ Signed-off-by: Ralf Baechle <r...@linux-mips.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- arch/mips/loongson64/loongson-3/smp.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) --- a/arch/mips/loongson64/loongson-3/smp.c +++ b/arch/mips/loongson64/loongson-3/smp.c @@ -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_r 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(voi 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); }
