You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
61 lines
2.3 KiB
61 lines
2.3 KiB
2 years ago
|
commit 58d2672f64176fcb323859d3bd5240fb1cf8f25c
|
||
|
|
Author: Wilco Dijkstra <wdijkstr@arm.com>
|
||
|
|
Date: Fri May 10 16:38:21 2019 +0100
|
||
|
|
|
||
|
|
Fix tcache count maximum (BZ #24531)
|
||
|
|
|
||
|
|
The tcache counts[] array is a char, which has a very small range and thus
|
||
|
|
may overflow. When setting tcache_count tunable, there is no overflow check.
|
||
|
|
However the tunable must not be larger than the maximum value of the tcache
|
||
|
|
counts[] array, otherwise it can overflow when filling the tcache.
|
||
|
|
|
||
|
|
[BZ #24531]
|
||
|
|
* malloc/malloc.c (MAX_TCACHE_COUNT): New define.
|
||
|
|
(do_set_tcache_count): Only update if count is small enough.
|
||
|
|
* manual/tunables.texi (glibc.malloc.tcache_count): Document max value.
|
||
|
|
|
||
|
|
(cherry picked from commit 5ad533e8e65092be962e414e0417112c65d154fb)
|
||
|
|
|
||
|
|
diff --git a/malloc/malloc.c b/malloc/malloc.c
|
||
|
|
index 723d393f529bdb4c..92239b3324584060 100644
|
||
|
|
--- a/malloc/malloc.c
|
||
|
|
+++ b/malloc/malloc.c
|
||
|
|
@@ -2919,6 +2919,8 @@ typedef struct tcache_perthread_struct
|
||
|
|
tcache_entry *entries[TCACHE_MAX_BINS];
|
||
|
|
} tcache_perthread_struct;
|
||
|
|
|
||
|
|
+#define MAX_TCACHE_COUNT 127 /* Maximum value of counts[] entries. */
|
||
|
|
+
|
||
|
|
static __thread bool tcache_shutting_down = false;
|
||
|
|
static __thread tcache_perthread_struct *tcache = NULL;
|
||
|
|
|
||
|
|
@@ -5124,8 +5126,11 @@ static inline int
|
||
|
|
__always_inline
|
||
|
|
do_set_tcache_count (size_t value)
|
||
|
|
{
|
||
|
|
- LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
|
||
|
|
- mp_.tcache_count = value;
|
||
|
|
+ if (value <= MAX_TCACHE_COUNT)
|
||
|
|
+ {
|
||
|
|
+ LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count);
|
||
|
|
+ mp_.tcache_count = value;
|
||
|
|
+ }
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
diff --git a/manual/tunables.texi b/manual/tunables.texi
|
||
|
|
index bb4819bdf1de273e..9dccf2ee7f8eec17 100644
|
||
|
|
--- a/manual/tunables.texi
|
||
|
|
+++ b/manual/tunables.texi
|
||
|
|
@@ -188,8 +188,8 @@ per-thread cache. The default (and maximum) value is 1032 bytes on
|
||
|
|
|
||
|
|
@deftp Tunable glibc.malloc.tcache_count
|
||
|
|
The maximum number of chunks of each size to cache. The default is 7.
|
||
|
|
-There is no upper limit, other than available system memory. If set
|
||
|
|
-to zero, the per-thread cache is effectively disabled.
|
||
|
|
+The upper limit is 127. If set to zero, the per-thread cache is effectively
|
||
|
|
+disabled.
|
||
|
|
|
||
|
|
The approximate maximum overhead of the per-thread cache is thus equal
|
||
|
|
to the number of bins times the chunk count in each bin times the size
|