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Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile
* 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:
commit
c12ae95ccc
3 changed files with 39 additions and 29 deletions
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@ -840,7 +840,7 @@ static int __init topology_init(void)
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for_each_online_node(i)
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for_each_online_node(i)
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register_one_node(i);
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register_one_node(i);
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for_each_present_cpu(i)
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for (i = 0; i < smp_height * smp_width; ++i)
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register_cpu(&cpu_devices[i], i);
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register_cpu(&cpu_devices[i], i);
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return 0;
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return 0;
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@ -18,12 +18,24 @@
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void *memchr(const void *s, int c, size_t n)
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void *memchr(const void *s, int c, size_t n)
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{
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{
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const uint32_t *last_word_ptr;
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const uint32_t *p;
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const char *last_byte_ptr;
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uintptr_t s_int;
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uint32_t goal, before_mask, v, bits;
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char *ret;
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if (__builtin_expect(n == 0, 0)) {
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/* Don't dereference any memory if the array is empty. */
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return NULL;
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}
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/* Get an aligned pointer. */
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/* Get an aligned pointer. */
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const uintptr_t s_int = (uintptr_t) s;
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s_int = (uintptr_t) s;
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const uint32_t *p = (const uint32_t *)(s_int & -4);
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p = (const uint32_t *)(s_int & -4);
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/* Create four copies of the byte for which we are looking. */
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/* Create four copies of the byte for which we are looking. */
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const uint32_t goal = 0x01010101 * (uint8_t) c;
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goal = 0x01010101 * (uint8_t) c;
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/* Read the first word, but munge it so that bytes before the array
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/* Read the first word, but munge it so that bytes before the array
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* will not match goal.
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* will not match goal.
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@ -31,23 +43,14 @@ void *memchr(const void *s, int c, size_t n)
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* Note that this shift count expression works because we know
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* Note that this shift count expression works because we know
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* shift counts are taken mod 32.
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* shift counts are taken mod 32.
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*/
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*/
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const uint32_t before_mask = (1 << (s_int << 3)) - 1;
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before_mask = (1 << (s_int << 3)) - 1;
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uint32_t v = (*p | before_mask) ^ (goal & before_mask);
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v = (*p | before_mask) ^ (goal & before_mask);
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/* Compute the address of the last byte. */
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/* Compute the address of the last byte. */
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const char *const last_byte_ptr = (const char *)s + n - 1;
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last_byte_ptr = (const char *)s + n - 1;
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/* Compute the address of the word containing the last byte. */
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/* Compute the address of the word containing the last byte. */
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const uint32_t *const last_word_ptr =
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last_word_ptr = (const uint32_t *)((uintptr_t) last_byte_ptr & -4);
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(const uint32_t *)((uintptr_t) last_byte_ptr & -4);
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uint32_t bits;
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char *ret;
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if (__builtin_expect(n == 0, 0)) {
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/* Don't dereference any memory if the array is empty. */
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return NULL;
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}
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while ((bits = __insn_seqb(v, goal)) == 0) {
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while ((bits = __insn_seqb(v, goal)) == 0) {
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if (__builtin_expect(p == last_word_ptr, 0)) {
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if (__builtin_expect(p == last_word_ptr, 0)) {
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@ -167,23 +167,30 @@ void arch_write_lock_slow(arch_rwlock_t *rwlock, u32 val)
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* when we compare them.
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* when we compare them.
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*/
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*/
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u32 my_ticket_;
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u32 my_ticket_;
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u32 iterations = 0;
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/* Take out the next ticket; this will also stop would-be readers. */
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if (val & 1)
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val = get_rwlock(rwlock);
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rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT);
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/* Extract my ticket value from the original word. */
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my_ticket_ = val >> WR_NEXT_SHIFT;
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/*
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/*
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* Wait until the "current" field matches our ticket, and
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* Wait until there are no readers, then bump up the next
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* there are no remaining readers.
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* field and capture the ticket value.
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*/
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*/
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for (;;) {
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if (!(val & 1)) {
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if ((val >> RD_COUNT_SHIFT) == 0)
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break;
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rwlock->lock = val;
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}
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delay_backoff(iterations++);
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val = __insn_tns((int *)&rwlock->lock);
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}
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/* Take out the next ticket and extract my ticket value. */
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rwlock->lock = __insn_addb(val, 1 << WR_NEXT_SHIFT);
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my_ticket_ = val >> WR_NEXT_SHIFT;
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/* Wait until the "current" field matches our ticket. */
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for (;;) {
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for (;;) {
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u32 curr_ = val >> WR_CURR_SHIFT;
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u32 curr_ = val >> WR_CURR_SHIFT;
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u32 readers = val >> RD_COUNT_SHIFT;
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u32 delta = ((my_ticket_ - curr_) & WR_MASK);
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u32 delta = ((my_ticket_ - curr_) & WR_MASK) + !!readers;
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if (likely(delta == 0))
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if (likely(delta == 0))
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break;
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break;
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