From ba6edfcd1708da2e665f14eee76e87f39448ec40 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 10 Apr 2006 22:53:58 -0700 Subject: [PATCH] [PATCH] timer initialisation fix We need the boot CPU's tvec_bases[] entry to be initialised super-early in boot, for early_serial_setup(). That runs within setup_arch(), before even per-cpu areas are initialised. The patch changes tvec_bases to use compile-time initialisation, and adds a separate array `tvec_base_done' to keep track of which CPU has had its tvec_bases[] entry initialised (because we can no longer use the zeroness of that tvec_bases[] entry to determine whether it has been initialised). Thanks to Eugene Surovegin for diagnosing this. Cc: Eugene Surovegin Cc: Jan Beulich Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/timer.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/kernel/timer.c b/kernel/timer.c index 471ab8710b8f..883773788836 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -81,9 +81,10 @@ struct tvec_t_base_s { } ____cacheline_aligned_in_smp; typedef struct tvec_t_base_s tvec_base_t; -static DEFINE_PER_CPU(tvec_base_t *, tvec_bases); + tvec_base_t boot_tvec_bases; EXPORT_SYMBOL(boot_tvec_bases); +static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = { &boot_tvec_bases }; static inline void set_running_timer(tvec_base_t *base, struct timer_list *timer) @@ -1224,28 +1225,36 @@ static int __devinit init_timers_cpu(int cpu) { int j; tvec_base_t *base; + static char __devinitdata tvec_base_done[NR_CPUS]; - base = per_cpu(tvec_bases, cpu); - if (!base) { + if (!tvec_base_done[cpu]) { static char boot_done; - /* - * Cannot do allocation in init_timers as that runs before the - * allocator initializes (and would waste memory if there are - * more possible CPUs than will ever be installed/brought up). - */ if (boot_done) { + /* + * The APs use this path later in boot + */ base = kmalloc_node(sizeof(*base), GFP_KERNEL, cpu_to_node(cpu)); if (!base) return -ENOMEM; memset(base, 0, sizeof(*base)); + per_cpu(tvec_bases, cpu) = base; } else { - base = &boot_tvec_bases; + /* + * This is for the boot CPU - we use compile-time + * static initialisation because per-cpu memory isn't + * ready yet and because the memory allocators are not + * initialised either. + */ boot_done = 1; + base = &boot_tvec_bases; } - per_cpu(tvec_bases, cpu) = base; + tvec_base_done[cpu] = 1; + } else { + base = per_cpu(tvec_bases, cpu); } + spin_lock_init(&base->lock); for (j = 0; j < TVN_SIZE; j++) { INIT_LIST_HEAD(base->tv5.vec + j); -- 2.30.2