Commit ba6edfcd authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

[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 <ebs@ebshome.net> for diagnosing this.

Cc: Eugene Surovegin <ebs@ebshome.net>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5246d050

kernel/timer.c

+19 −10
Original line number Diff line number Diff line
@@ -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;



		if (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).

			 * The APs use this path later in boot

			 */

		if (boot_done) {

			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);

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