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Date: Tue, 27 Oct 2009 13:32:21 +0100 (CET)
From: Jiri Kosina <jkosina@...e.cz>
To: Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
Tejun Heo <tj@...nel.org>, Jeff Mahoney <jeffm@...e.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Tony Luck <tony.luck@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>, linux-ia64@...r.kernel.org
Subject: [PATCH 1/2] 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().
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
mm/percpu.c | 25 +++++++++++++------------
1 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index 6af78c1..6b82bbf 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -366,7 +366,7 @@ 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 +376,7 @@ 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 +384,7 @@ 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 +393,7 @@ 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 +1047,7 @@ 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 +1056,13 @@ 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 +1080,7 @@ 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 +1097,7 @@ 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 +1105,16 @@ 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 +1126,7 @@ 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) {
--
1.6.4.2
--
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