Anand reports that the static buffers used for pertty size strings cause
a stack overflow on SPARC. Zach proposed to change the printf format to
wrap the number and the suffix into a macro. This would require to
change all callsites of pretty_size* and is not very convienient to
write.
This patch replaces the per-call-site static buffers with a limited
number for slots that would be used on each invokation of pretty_size
and wrap around. The number of array slots shall be 10 for now, in
current codebase there are no more than 2 calls to pretty_size in a
single argument list.
Reported-by: Anand Jain <Anand.Jain@xxxxxxxxxx>
CC: Zach Brown <zab@xxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxx>
---
Anand, please test on a real SPARC machine.
utils.c | 18 ++++++++++++++++++
utils.h | 8 ++------
3 files changed, 21 insertions(+), 6 deletions(-)
--- a/utils.c
+++ b/utils.c
@@ -1366,6 +1366,24 @@ out:
return ret;
}
+/*
+ * Note: this function uses a static per-thread buffer. Do not call this
+ * function more than 10 times within one argument list!
+ */
+const char *pretty_size_mode(u64 size, unsigned mode)
+{
+ static __thread int ps_index = 0;
+ static __thread char ps_array[10][32];
+ char *ret;
+
+ ret = ps_array[ps_index];
+ ps_index++;
+ ps_index %= 10;
+ (void)pretty_size_snprintf(size, ret, 32, mode);
+
+ return ret;
+}
+
static const char* unit_suffix_binary[] =
{ "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"};
static const char* unit_suffix_decimal[] =
diff --git a/utils.h b/utils.h
index 82ab5e82a3ff..539797c705b4 100644
--- a/utils.h
+++ b/utils.h
@@ -103,12 +103,7 @@ int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
int pretty_size_snprintf(u64 size, char *str, size_t str_bytes, unsigned unit_mode);
#define pretty_size(size) pretty_size_mode(size, UNITS_DEFAULT)
-#define pretty_size_mode(size, mode) \
- ({ \
- static __thread char _str[32]; \
- (void)pretty_size_snprintf((size), _str, sizeof(_str), (mode)); \
- _str; \
- })
+const char *pretty_size_mode(u64 size, unsigned mode);
int get_mountpt(char *dev, char *mntpt, size_t size);
int btrfs_scan_block_devices(int run_ioctl);
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