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Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile

Browse source 
* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
  arch/tile: fix memchr() not to dereference memory for zero length
  arch/tile: make glibc's sysconf(_SC_NPROCESSORS_CONF) work correctly
  arch/tile: fix rwlock so would-be write lockers don't block new readers
This commit is contained in:
Linus Torvalds 2010-11-25 07:42:32 +09:00
commit c12ae95ccc
3 changed files with 39 additions and 29 deletions
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2
arch/tile/kernel/setup.c
View file

@ -840,7 +840,7 @@ static int __init topology_init(void)
for_each_online_node(i)
register_one_node(i);
for_each_present_cpu(i)
for (i = 0; i < smp_height * smp_width; ++i)
register_cpu(&cpu_devices[i], i);
return 0;

35
arch/tile/lib/memchr_32.c
View file

@ -18,12 +18,24 @@
void *memchr(const void *s, int c, size_t n)
{
const uint32_t *last_word_ptr;
const uint32_t *p;
const char *last_byte_ptr;
uintptr_t s_int;
uint32_t goal, before_mask, v, bits;
char *ret;
if (__builtin_expect(n == 0, 0)) {
/* Don't dereference any memory if the array is empty. */
return NULL;
}
/* Get an aligned pointer. */
const uintptr_t s_int = (uintptr_t) s;
const uint32_t *p = (const uint32_t *)(s_int & -4);
s_int = (uintptr_t) s;
p = (const uint32_t *)(s_int & -4);
/* Create four copies of the byte for which we are looking. */
const uint32_t goal = 0x01010101 * (uint8_t) c;
goal = 0x01010101 * (uint8_t) c;
/* Read the first word, but munge it so that bytes before the array
* will not match goal.
@ -31,23 +43,14 @@ void *memchr(const void *s, int c, size_t n)
* Note that this shift count expression works because we know
* shift counts are taken mod 32.
*/
const uint32_t before_mask = (1 << (s_int << 3)) - 1;
uint32_t v = (*p | before_mask) ^ (goal & before_mask);
before_mask = (1 << (s_int << 3)) - 1;
v = (*p | before_mask) ^ (goal & before_mask);
/* Compute the address of the last byte. */
const char *const last_byte_ptr = (const char *)s + n - 1;
last_byte_ptr = (const char *)s + n - 1;
/* Compute the address of the word containing the last byte. */
const uint32_t *const last_word_ptr =
(const uint32_t *)((uintptr_t) last_byte_ptr & -4);
uint32_t bits;
char *ret;
if (__builtin_expect(n == 0, 0)) {
/* Don't dereference any memory if the array is empty. */
return NULL;
}
last_word_ptr = (const uint32_t *)((uintptr_t) last_byte_ptr & -4);
while ((bits = __insn_seqb(v, goal)) == 0) {
if (__builtin_expect(p == last_word_ptr, 0)) {

31
arch/tile/lib/spinlock_32.c
View file

@ -167,23 +167,30 @@ void arch_write_lock_slow(arch_rwlock_t *rwlock, u32 val)
* when we compare them.
*/
u32 my_ticket_;
/* Take out the next ticket; this will also stop would-be readers. */
if (val & 1)
val = get_rwlock(rwlock);
rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT);
/* Extract my ticket value from the original word. */
my_ticket_ = val >> WR_NEXT_SHIFT;
u32 iterations = 0;
/*
* Wait until the "current" field matches our ticket, and
* there are no remaining readers.
* Wait until there are no readers, then bump up the next
* field and capture the ticket value.
*/
for (;;) {
if (!(val & 1)) {
if ((val >> RD_COUNT_SHIFT) == 0)
break;
rwlock->lock = val;
}
delay_backoff(iterations++);
val = __insn_tns((int *)&rwlock->lock);
}
/* Take out the next ticket and extract my ticket value. */
rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT);
my_ticket_ = val >> WR_NEXT_SHIFT;
/* Wait until the "current" field matches our ticket. */
for (;;) {
u32 curr_ = val >> WR_CURR_SHIFT;
u32 readers = val >> RD_COUNT_SHIFT;
u32 delta = ((my_ticket_ - curr_) & WR_MASK) + !!readers;
u32 delta = ((my_ticket_ - curr_) & WR_MASK);
if (likely(delta == 0))
break;