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Subject[PATCH 4.14 12/57] include/trace/events/writeback.h: fix -Wstringop-truncation warnings
Date
From: Qian Cai <cai@lca.pw>

[ Upstream commit d1a445d3b86c9341ce7a0954c23be0edb5c9bec5 ]

There are many of those warnings.

In file included from ./arch/powerpc/include/asm/paca.h:15,
from ./arch/powerpc/include/asm/current.h:13,
from ./include/linux/thread_info.h:21,
from ./include/asm-generic/preempt.h:5,
from ./arch/powerpc/include/generated/asm/preempt.h:1,
from ./include/linux/preempt.h:78,
from ./include/linux/spinlock.h:51,
from fs/fs-writeback.c:19:
In function 'strncpy',
inlined from 'perf_trace_writeback_page_template' at
./include/trace/events/writeback.h:56:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified
bound 32 equals destination size [-Wstringop-truncation]
return __builtin_strncpy(p, q, size);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix it by using the new strscpy_pad() which was introduced in "lib/string:
Add strscpy_pad() function" and will always be NUL-terminated instead of
strncpy(). Also, change strlcpy() to use strscpy_pad() in this file for
consistency.

Link: http://lkml.kernel.org/r/1564075099-27750-1-git-send-email-cai@lca.pw
Fixes: 455b2864686d ("writeback: Initial tracing support")
Fixes: 028c2dd184c0 ("writeback: Add tracing to balance_dirty_pages")
Fixes: e84d0a4f8e39 ("writeback: trace event writeback_queue_io")
Fixes: b48c104d2211 ("writeback: trace event bdi_dirty_ratelimit")
Fixes: cc1676d917f3 ("writeback: Move requeueing when I_SYNC set to writeback_sb_inodes()")
Fixes: 9fb0a7da0c52 ("writeback: add more tracepoints")
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nitin Gote <nitin.r.gote@intel.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Stephen Kitt <steve@sk2.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/trace/events/writeback.h | 38 +++++++++++++++++---------------
1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 627f5759b67d1..a8066afb4b0ef 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -65,8 +65,9 @@ TRACE_EVENT(writeback_dirty_page,
),

TP_fast_assign(
- strncpy(__entry->name,
- mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
+ strscpy_pad(__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;
),
@@ -95,8 +96,8 @@ 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,
- bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+ strscpy_pad(__entry->name,
+ bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->flags = flags;
@@ -175,8 +176,8 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
),

TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
__entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc);
@@ -219,8 +220,9 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name,
- wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
+ strscpy_pad(__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;
__entry->sync_mode = work->sync_mode;
@@ -273,7 +275,7 @@ DECLARE_EVENT_CLASS(writeback_class,
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__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 +298,7 @@ TRACE_EVENT(writeback_bdi_register,
__array(char, name, 32)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__entry->name, dev_name(bdi->dev), 32);
),
TP_printk("bdi %s",
__entry->name
@@ -321,7 +323,7 @@ DECLARE_EVENT_CLASS(wbc_class,
),

TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__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 +374,7 @@ TRACE_EVENT(writeback_queue_io,
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strncpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
__entry->older = dirtied_before;
__entry->age = (jiffies - dirtied_before) * 1000 / HZ;
__entry->moved = moved;
@@ -457,7 +459,7 @@ TRACE_EVENT(bdi_dirty_ratelimit,
),

TP_fast_assign(
- strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);
__entry->write_bw = KBps(wb->write_bandwidth);
__entry->avg_write_bw = KBps(wb->avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
@@ -522,7 +524,7 @@ TRACE_EVENT(balance_dirty_pages,

TP_fast_assign(
unsigned long freerun = (thresh + bg_thresh) / 2;
- strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);

__entry->limit = global_wb_domain.dirty_limit;
__entry->setpoint = (global_wb_domain.dirty_limit +
@@ -582,8 +584,8 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
),

TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
@@ -656,8 +658,8 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
),

TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
--
2.27.0


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