From 403a91b1659cb149dbddc5885f892734ae4542d8 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Thu, 29 Oct 2009 00:25:59 +0900 Subject: percpu: allow pcpu_alloc() to be called with IRQs off pcpu_alloc() and pcpu_extend_area_map() perform a series of spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe with respect to being called from contexts which have IRQs off. This patch converts the code to perform save/restore of flags instead, making pcpu_alloc() (or __alloc_percpu() respectively) to be called from early kernel startup stage, where IRQs are off. This is needed for proper initialization of per-cpu rq_weight data from sched_init(). tj: added comment explaining why irqsave/restore is used in alloc path. Signed-off-by: Jiri Kosina Acked-by: Ingo Molnar Signed-off-by: Tejun Heo --- mm/percpu.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index 6af78c1ee70..d90797160c2 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -153,7 +153,10 @@ static int pcpu_reserved_chunk_limit; * * During allocation, pcpu_alloc_mutex is kept locked all the time and * pcpu_lock is grabbed and released as necessary. All actual memory - * allocations are done using GFP_KERNEL with pcpu_lock released. + * allocations are done using GFP_KERNEL with pcpu_lock released. In + * general, percpu memory can't be allocated with irq off but + * irqsave/restore are still used in alloc path so that it can be used + * from early init path - sched_init() specifically. * * Free path accesses and alters only the index data structures, so it * can be safely called from atomic context. When memory needs to be @@ -366,7 +369,7 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) * RETURNS: * 0 if noop, 1 if successfully extended, -errno on failure. */ -static int pcpu_extend_area_map(struct pcpu_chunk *chunk) +static int pcpu_extend_area_map(struct pcpu_chunk *chunk, unsigned long *flags) { int new_alloc; int *new; @@ -376,7 +379,7 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk) if (chunk->map_alloc >= chunk->map_used + 2) return 0; - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, *flags); new_alloc = PCPU_DFL_MAP_ALLOC; while (new_alloc < chunk->map_used + 2) @@ -384,7 +387,7 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk) new = pcpu_mem_alloc(new_alloc * sizeof(new[0])); if (!new) { - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, *flags); return -ENOMEM; } @@ -393,7 +396,7 @@ static int pcpu_extend_area_map(struct pcpu_chunk *chunk) * could have happened inbetween, so map_used couldn't have * grown. */ - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, *flags); BUG_ON(new_alloc < chunk->map_used + 2); size = chunk->map_alloc * sizeof(chunk->map[0]); @@ -1047,6 +1050,7 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved) struct pcpu_chunk *chunk; const char *err; int slot, off; + unsigned long flags; if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) { WARN(true, "illegal size (%zu) or align (%zu) for " @@ -1055,13 +1059,13 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved) } mutex_lock(&pcpu_alloc_mutex); - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, flags); /* serve reserved allocations from the reserved chunk if available */ if (reserved && pcpu_reserved_chunk) { chunk = pcpu_reserved_chunk; if (size > chunk->contig_hint || - pcpu_extend_area_map(chunk) < 0) { + pcpu_extend_area_map(chunk, &flags) < 0) { err = "failed to extend area map of reserved chunk"; goto fail_unlock; } @@ -1079,7 +1083,7 @@ restart: if (size > chunk->contig_hint) continue; - switch (pcpu_extend_area_map(chunk)) { + switch (pcpu_extend_area_map(chunk, &flags)) { case 0: break; case 1: @@ -1096,7 +1100,7 @@ restart: } /* hmmm... no space left, create a new chunk */ - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, flags); chunk = alloc_pcpu_chunk(); if (!chunk) { @@ -1104,16 +1108,16 @@ restart: goto fail_unlock_mutex; } - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, flags); pcpu_chunk_relocate(chunk, -1); goto restart; area_found: - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, flags); /* populate, map and clear the area */ if (pcpu_populate_chunk(chunk, off, size)) { - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, flags); pcpu_free_area(chunk, off); err = "failed to populate"; goto fail_unlock; @@ -1125,7 +1129,7 @@ area_found: return __addr_to_pcpu_ptr(chunk->base_addr + off); fail_unlock: - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, flags); fail_unlock_mutex: mutex_unlock(&pcpu_alloc_mutex); if (warn_limit) { -- cgit v1.2.3-70-g09d2