2018-05-29 06:38:46

by Nick Desaulniers

Subject: [PATCH] writeback: tracing: prefer strlcpy to strncpy

Fixes a stringop-truncation warning from gcc-8.

Signed-off-by: Nick Desaulniers <[email protected]>
---
include/trace/events/writeback.h | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 32db72c..cfaf57d 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -66,7 +66,7 @@ TRACE_EVENT(writeback_dirty_page,
),

TP_fast_assign(
- strncpy(__entry->name,
+ strlcpy(__entry->name,
mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
__entry->ino = mapping ? mapping->host->i_ino : 0;
__entry->index = page->index;
@@ -96,7 +96,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
struct backing_dev_info *bdi = inode_to_bdi(inode);

/* may be called for files on pseudo FSes w/ unregistered bdi */
- strncpy(__entry->name,
+ strlcpy(__entry->name,
bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
@@ -176,7 +176,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
),

TP_fast_assign(
- strncpy(__entry->name,
+ strlcpy(__entry->name,
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
@@ -220,7 +220,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name,
+ strlcpy(__entry->name,
wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
@@ -274,7 +274,7 @@ DECLARE_EVENT_CLASS(writeback_class,
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strlcpy(__entry->name, dev_name(wb->bdi->dev), 32);
__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
),
TP_printk("bdi %s: cgroup_ino=%u",
@@ -296,7 +296,7 @@ TRACE_EVENT(writeback_bdi_register,
__array(char, name, 32)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strlcpy(__entry->name, dev_name(bdi->dev), 32);
),
TP_printk("bdi %s",
__entry->name
@@ -321,7 +321,7 @@ DECLARE_EVENT_CLASS(wbc_class,
),

TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strlcpy(__entry->name, dev_name(bdi->dev), 32);
__entry->nr_to_write = wbc->nr_to_write;
__entry->pages_skipped = wbc->pages_skipped;
__entry->sync_mode = wbc->sync_mode;
@@ -372,7 +372,7 @@ TRACE_EVENT(writeback_queue_io,
),
TP_fast_assign(
unsigned long *older_than_this = work->older_than_this;
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strlcpy(__entry->name, dev_name(wb->bdi->dev), 32);
__entry->older = older_than_this ? *older_than_this : 0;
__entry->age = older_than_this ?
(jiffies - *older_than_this) * 1000 / HZ : -1;
@@ -583,7 +583,7 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
),

TP_fast_assign(
- strncpy(__entry->name,
+ strlcpy(__entry->name,
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
@@ -657,7 +657,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
),

TP_fast_assign(
- strncpy(__entry->name,
+ strlcpy(__entry->name,
dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
--
2.7.4

2018-05-30 01:58:07

by Nick Desaulniers

Subject: Re: [PATCH] writeback: tracing: prefer strlcpy to strncpy

On Mon, May 28, 2018 at 11:37 PM, Nick Desaulniers
<[email protected]> wrote:
> Fixes a stringop-truncation warning from gcc-8.
>
> Signed-off-by: Nick Desaulniers <[email protected]>
> ---
> include/trace/events/writeback.h | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
> index 32db72c..cfaf57d 100644
> --- a/include/trace/events/writeback.h
> +++ b/include/trace/events/writeback.h
> @@ -66,7 +66,7 @@ TRACE_EVENT(writeback_dirty_page,
> ),
>
> TP_fast_assign(
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
> __entry->ino = mapping ? mapping->host->i_ino : 0;
> __entry->index = page->index;
> @@ -96,7 +96,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
> struct backing_dev_info *bdi = inode_to_bdi(inode);
>
> /* may be called for files on pseudo FSes w/ unregistered bdi */
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
> __entry->ino = inode->i_ino;
> __entry->state = inode->i_state;
> @@ -176,7 +176,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
> ),
>
> TP_fast_assign(
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> dev_name(inode_to_bdi(inode)->dev), 32);
> __entry->ino = inode->i_ino;
> __entry->sync_mode = wbc->sync_mode;
> @@ -220,7 +220,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
> __field(unsigned int, cgroup_ino)
> ),
> TP_fast_assign(
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
> __entry->nr_pages = work->nr_pages;
> __entry->sb_dev = work->sb ? work->sb->s_dev : 0;
> @@ -274,7 +274,7 @@ DECLARE_EVENT_CLASS(writeback_class,
> __field(unsigned int, cgroup_ino)
> ),
> TP_fast_assign(
> - strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
> + strlcpy(__entry->name, dev_name(wb->bdi->dev), 32);
> __entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
> ),
> TP_printk("bdi %s: cgroup_ino=%u",
> @@ -296,7 +296,7 @@ TRACE_EVENT(writeback_bdi_register,
> __array(char, name, 32)
> ),
> TP_fast_assign(
> - strncpy(__entry->name, dev_name(bdi->dev), 32);
> + strlcpy(__entry->name, dev_name(bdi->dev), 32);
> ),
> TP_printk("bdi %s",
> __entry->name
> @@ -321,7 +321,7 @@ DECLARE_EVENT_CLASS(wbc_class,
> ),
>
> TP_fast_assign(
> - strncpy(__entry->name, dev_name(bdi->dev), 32);
> + strlcpy(__entry->name, dev_name(bdi->dev), 32);
> __entry->nr_to_write = wbc->nr_to_write;
> __entry->pages_skipped = wbc->pages_skipped;
> __entry->sync_mode = wbc->sync_mode;
> @@ -372,7 +372,7 @@ TRACE_EVENT(writeback_queue_io,
> ),
> TP_fast_assign(
> unsigned long *older_than_this = work->older_than_this;
> - strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
> + strlcpy(__entry->name, dev_name(wb->bdi->dev), 32);
> __entry->older = older_than_this ? *older_than_this : 0;
> __entry->age = older_than_this ?
> (jiffies - *older_than_this) * 1000 / HZ : -1;
> @@ -583,7 +583,7 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
> ),
>
> TP_fast_assign(
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> dev_name(inode_to_bdi(inode)->dev), 32);
> __entry->ino = inode->i_ino;
> __entry->state = inode->i_state;
> @@ -657,7 +657,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
> ),
>
> TP_fast_assign(
> - strncpy(__entry->name,
> + strlcpy(__entry->name,
> dev_name(inode_to_bdi(inode)->dev), 32);
> __entry->ino = inode->i_ino;
> __entry->state = inode->i_state;
> --
> 2.7.4
>

Eric points out this wont initialize the rest of the dest if src if
less than size.