When compiled with W=1, we get:
block/blk-throttle.c: In function ‘tg_prfill_limit’:
block/blk-throttle.c:1539:74: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
| ^
block/blk-throttle.c:1539:25: note: ‘snprintf’ output between 8 and 27 bytes into a destination of size 26
1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1540 | tg->idletime_threshold_conf);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
block/blk-throttle.c:1546:43: error: ‘%lu’ directive output may be truncated writing between 1 and 20 bytes into a region of size 17 [-Werror=format-truncation=]
1546 | " latency=%lu", tg->latency_target_conf);
| ^~~
block/blk-throttle.c:1546:33: note: directive argument in the range [0, 18446744073709551614]
1546 | " latency=%lu", tg->latency_target_conf);
| ^~~~~~~~~~~~~~
block/blk-throttle.c:1545:25: note: ‘snprintf’ output between 11 and 30 bytes into a destination of size 26
1545 | snprintf(latency_time, sizeof(latency_time),
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1546 | " latency=%lu", tg->latency_target_conf);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In order to fix it, remove all the intermediate buffers and write directly
into the 'sf' seq_file.
Fixes: ada75b6e5b2a ("blk-throttle: add interface to configure idle time threshold")
Fixes: ec80991d6fc2 ("blk-throttle: add interface for per-cgroup target latency")
Signed-off-by: Christophe JAILLET <[email protected]>
---
block/blk-throttle.c | 52 +++++++++++++++++++++++++-------------------
1 file changed, 30 insertions(+), 22 deletions(-)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 16f5766620a4..470a8a4ed68e 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1494,11 +1494,8 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
{
struct throtl_grp *tg = pd_to_tg(pd);
const char *dname = blkg_dev_name(pd->blkg);
- char bufs[4][21] = { "max", "max", "max", "max" };
u64 bps_dft;
unsigned int iops_dft;
- char idle_time[26] = "";
- char latency_time[26] = "";
if (!dname)
return 0;
@@ -1520,35 +1517,46 @@ static u64 tg_prfill_limit(struct seq_file *sf, struct blkg_policy_data *pd,
tg->latency_target_conf == DFL_LATENCY_TARGET)))
return 0;
+ seq_printf(sf, "%s", dname);
+
+ seq_puts(sf, " rbps=");
if (tg->bps_conf[READ][off] != U64_MAX)
- snprintf(bufs[0], sizeof(bufs[0]), "%llu",
- tg->bps_conf[READ][off]);
+ seq_printf(sf, "%llu", tg->bps_conf[READ][off]);
+ else
+ seq_puts(sf, "max");
+
+ seq_puts(sf, " wbps=");
if (tg->bps_conf[WRITE][off] != U64_MAX)
- snprintf(bufs[1], sizeof(bufs[1]), "%llu",
- tg->bps_conf[WRITE][off]);
+ seq_printf(sf, "%llu", tg->bps_conf[WRITE][off]);
+ else
+ seq_puts(sf, "max");
+
+ seq_puts(sf, " riops=");
if (tg->iops_conf[READ][off] != UINT_MAX)
- snprintf(bufs[2], sizeof(bufs[2]), "%u",
- tg->iops_conf[READ][off]);
+ seq_printf(sf, "%u", tg->iops_conf[READ][off]);
+ else
+ seq_puts(sf, "max");
+
+ seq_puts(sf, " wiops=");
if (tg->iops_conf[WRITE][off] != UINT_MAX)
- snprintf(bufs[3], sizeof(bufs[3]), "%u",
- tg->iops_conf[WRITE][off]);
+ seq_printf(sf, "%u", tg->iops_conf[WRITE][off]);
+ else
+ seq_puts(sf, "max");
+
if (off == LIMIT_LOW) {
- if (tg->idletime_threshold_conf == ULONG_MAX)
- strcpy(idle_time, " idle=max");
+ seq_puts(sf, " idle=");
+ if (tg->idletime_threshold_conf != ULONG_MAX)
+ seq_printf(sf, "%lu", tg->idletime_threshold_conf);
else
- snprintf(idle_time, sizeof(idle_time), " idle=%lu",
- tg->idletime_threshold_conf);
+ seq_puts(sf, "max");
- if (tg->latency_target_conf == ULONG_MAX)
- strcpy(latency_time, " latency=max");
+ seq_puts(sf, " latency=");
+ if (tg->latency_target_conf != ULONG_MAX)
+ seq_printf(sf, "%lu", tg->latency_target_conf);
else
- snprintf(latency_time, sizeof(latency_time),
- " latency=%lu", tg->latency_target_conf);
+ seq_puts(sf, "max");
}
- seq_printf(sf, "%s rbps=%s wbps=%s riops=%s wiops=%s%s%s\n",
- dname, bufs[0], bufs[1], bufs[2], bufs[3], idle_time,
- latency_time);
return 0;
}
--
2.34.1
On Sat, Dec 16, 2023 at 01:54:56PM +0100, Christophe JAILLET wrote:
> When compiled with W=1, we get:
> block/blk-throttle.c: In function ‘tg_prfill_limit’:
> block/blk-throttle.c:1539:74: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
> 1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
> | ^
> block/blk-throttle.c:1539:25: note: ‘snprintf’ output between 8 and 27 bytes into a destination of size 26
> 1539 | snprintf(idle_time, sizeof(idle_time), " idle=%lu",
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1540 | tg->idletime_threshold_conf);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> block/blk-throttle.c:1546:43: error: ‘%lu’ directive output may be truncated writing between 1 and 20 bytes into a region of size 17 [-Werror=format-truncation=]
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ^~~
> block/blk-throttle.c:1546:33: note: directive argument in the range [0, 18446744073709551614]
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ^~~~~~~~~~~~~~
> block/blk-throttle.c:1545:25: note: ‘snprintf’ output between 11 and 30 bytes into a destination of size 26
> 1545 | snprintf(latency_time, sizeof(latency_time),
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1546 | " latency=%lu", tg->latency_target_conf);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> In order to fix it, remove all the intermediate buffers and write directly
> into the 'sf' seq_file.
>
> Fixes: ada75b6e5b2a ("blk-throttle: add interface to configure idle time threshold")
> Fixes: ec80991d6fc2 ("blk-throttle: add interface for per-cgroup target latency")
I'm not sure Fixes tags are necessary here given that this isn't something
we'd hit in practice.
> Signed-off-by: Christophe JAILLET <[email protected]>
Looks fine to me, so:
Acked-by: Tejun Heo <[email protected]>
But, can you please briefly explain how you tested the patch?
Thanks.
--
tejun