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Subject[PATCH] writeback: verify that underlying dev exists before getting its name
Date
We can't assume there is always an underlying device and must verify that
as well. Otherwise, we'd deref a NULL ptr here.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
include/trace/events/writeback.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index fff846b..8f9efaa 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -66,7 +66,9 @@ TRACE_EVENT(writeback_dirty_page,

TP_fast_assign(
strncpy(__entry->name,
- mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32);
+ mapping && inode_to_bdi(mapping->host)->dev ?
+ dev_name(inode_to_bdi(mapping->host)->dev) :
+ "(unknown)", 32);
__entry->ino = mapping ? mapping->host->i_ino : 0;
__entry->index = page->index;
),
--
1.7.10.4


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