Hi,
Looking at this diff and the previous one, I found some more possible
cleanups for malloc.c (the patch below is to be applied after both of
them, even if the second one has not been committed yet):
1. In malloc_bytes(), use ffs(3) instead of manual loops, which on many
architectures boils down to merely one or two instructions (for example,
see src/lib/libc/arch/amd64/string/ffs.S).
2. Slightly reorder find_chunksize() to avoid checking twice for the
same condition.
3. Remove the outdated comment above omalloc_poolinit().
4. Remove extra braces enclosing a switch case, made unnecessary by
revision 1.233.
5. Some miscellaneous style and whitespace fixes.
--- malloc.c.orig Fri Dec 29 00:06:24 2017
+++ malloc.c Fri Dec 29 06:02:04 2017
@@ -376,12 +376,11 @@ omalloc_parseopt(char opt)
case 'X':
mopts.malloc_xmalloc = 1;
break;
- default: {
+ default:
dprintf(STDERR_FILENO, "malloc() warning: "
- "unknown char in MALLOC_OPTIONS\n");
+ "unknown char in MALLOC_OPTIONS\n");
break;
}
- }
}
static void
@@ -448,9 +447,6 @@ omalloc_init(void)
;
}
-/*
- * Initialize a dir_info, which should have been cleared by caller
- */
static void
omalloc_poolinit(struct dir_info **dp)
{
@@ -502,7 +498,7 @@ omalloc_grow(struct dir_info *d)
size_t i;
struct region_info *p;
- if (d->regions_total > SIZE_MAX / sizeof(struct region_info) / 2 )
+ if (d->regions_total > SIZE_MAX / sizeof(struct region_info) / 2)
return 1;
newtotal = d->regions_total * 2;
@@ -828,7 +824,7 @@ alloc_chunk_info(struct dir_info *d, int bits)
return NULL;
STATS_ADD(d->malloc_used, MALLOC_PAGESIZE);
count = MALLOC_PAGESIZE / size;
-
+
if (bits == 0) {
shift = 1;
i = MALLOC_MINSIZE - 1;
@@ -903,23 +899,21 @@ err:
static int
find_chunksize(size_t size)
{
- int i, j;
+ int r;
- /* Don't bother with anything less than this */
- /* unless we have a malloc(0) requests */
- if (size != 0 && size < MALLOC_MINSIZE)
+ /* malloc(0) is special */
+ if (size == 0)
+ return 0;
+
+ if (size < MALLOC_MINSIZE)
size = MALLOC_MINSIZE;
+ size--;
- /* Find the right bucket */
- if (size == 0)
- j = 0;
- else {
- j = MALLOC_MINSHIFT;
- i = (size - 1) >> (MALLOC_MINSHIFT - 1);
- while (i >>= 1)
- j++;
- }
- return j;
+ r = MALLOC_MINSHIFT;
+ while (size >> r != 0)
+ r++;
+
+ return r;
}
static void
@@ -941,7 +935,7 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
u_int i, r;
int j, listnum;
size_t k;
- u_short u, b, *lp;
+ u_short *lp;
struct chunk_info *bp;
void *p;
@@ -970,15 +964,12 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
/* start somewhere in a short */
lp = &bp->bits[i / MALLOC_BITS];
if (*lp) {
- b = *lp;
- k = i % MALLOC_BITS;
- u = 1 << k;
- while (k < MALLOC_BITS) {
- if (b & u)
- goto found;
- k++;
- u <<= 1;
- }
+ j = i % MALLOC_BITS;
+ k = ffs(*lp >> j);
+ if (k != 0) {
+ k += j - 1;
+ goto found;
+ }
}
/* no bit halfway, go to next full short */
i /= MALLOC_BITS;
@@ -986,16 +977,10 @@ malloc_bytes(struct dir_info *d, size_t size, void *f)
if (++i >= bp->total / MALLOC_BITS)
i = 0;
lp = &bp->bits[i];
- if (*lp) {
- b = *lp;
- k = 0;
- u = 1;
- for (;;) {
- if (b & u)
- goto found;
- k++;
- u <<= 1;
- }
+ k = ffs(*lp);
+ if (k != 0) {
+ k--;
+ break;
}
}
found:
@@ -1006,10 +991,10 @@ found:
}
#endif
- *lp ^= u;
+ *lp ^= 1 << k;
/* If there are no more free, remove from free-list */
- if (!--bp->free)
+ if (--bp->free == 0)
LIST_REMOVE(bp, entries);
/* Adjust to the real offset of that chunk */
@@ -1045,7 +1030,7 @@ validate_canary(struct dir_info *d, u_char *ptr, size_
if (*p != SOME_JUNK) {
wrterror(d, "chunk canary corrupted %p %#tx@%#zx%s",
ptr, p - ptr, sz, *p == SOME_FREEJUNK ?
- " (double free?)" : "");
+ " (double free?)" : "");
}
p++;
}
@@ -1169,8 +1154,7 @@ omalloc(struct dir_info *pool, size_t sz, int zero_fil
else
memset(p, SOME_JUNK,
psz - mopts.malloc_guard);
- }
- else if (mopts.chunk_canaries)
+ } else if (mopts.chunk_canaries)
fill_canary(p, sz - mopts.malloc_guard,
psz - mopts.malloc_guard);
}
@@ -1221,7 +1205,7 @@ _malloc_init(int from_rthreads)
max = from_rthreads ? _MALLOC_MUTEXES : 1;
if (((uintptr_t)&malloc_readonly & MALLOC_PAGEMASK) == 0)
mprotect(&malloc_readonly, sizeof(malloc_readonly),
- PROT_READ | PROT_WRITE);
+ PROT_READ | PROT_WRITE);
for (i = 0; i < max; i++) {
if (mopts.malloc_pool[i])
continue;
@@ -2026,8 +2010,7 @@ omemalign(struct dir_info *pool, size_t alignment, siz
SOME_JUNK, psz - sz);
else
memset(p, SOME_JUNK, psz - mopts.malloc_guard);
- }
- else if (mopts.chunk_canaries)
+ } else if (mopts.chunk_canaries)
fill_canary(p, sz - mopts.malloc_guard,
psz - mopts.malloc_guard);
Regards,
kshe
