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authorEric Dumazet <edumazet@google.com>2012-06-12 15:24:40 +0200
committerJens Axboe <axboe@kernel.dk>2012-06-13 21:16:42 +0200
commit047fe3605235888f3ebcda0c728cb31937eadfe6 (patch)
tree9c33ef4b076bd54f686afe924cee01e21c55f427 /include/linux/splice.h
parent27e1f9d1cc87be4e53c6eb7158cafc21c4b85a14 (diff)
downloadlinux-047fe3605235888f3ebcda0c728cb31937eadfe6.tar.gz
splice: fix racy pipe->buffers uses
Dave Jones reported a kernel BUG at mm/slub.c:3474! triggered by splice_shrink_spd() called from vmsplice_to_pipe() commit 35f3d14dbbc5 (pipe: add support for shrinking and growing pipes) added capability to adjust pipe->buffers. Problem is some paths don't hold pipe mutex and assume pipe->buffers doesn't change for their duration. Fix this by adding nr_pages_max field in struct splice_pipe_desc, and use it in place of pipe->buffers where appropriate. splice_shrink_spd() loses its struct pipe_inode_info argument. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Tom Herbert <therbert@google.com> Cc: stable <stable@vger.kernel.org> # 2.6.35 Tested-by: Dave Jones <davej@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/splice.h')
-rw-r--r--include/linux/splice.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 26e5b613deda..09a545a7dfa3 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -51,7 +51,8 @@ struct partial_page {
struct splice_pipe_desc {
struct page **pages; /* page map */
struct partial_page *partial; /* pages[] may not be contig */
- int nr_pages; /* number of pages in map */
+ int nr_pages; /* number of populated pages in map */
+ unsigned int nr_pages_max; /* pages[] & partial[] arrays size */
unsigned int flags; /* splice flags */
const struct pipe_buf_operations *ops;/* ops associated with output pipe */
void (*spd_release)(struct splice_pipe_desc *, unsigned int);
@@ -85,9 +86,8 @@ extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
/*
* for dynamic pipe sizing
*/
-extern int splice_grow_spd(struct pipe_inode_info *, struct splice_pipe_desc *);
-extern void splice_shrink_spd(struct pipe_inode_info *,
- struct splice_pipe_desc *);
+extern int splice_grow_spd(const struct pipe_inode_info *, struct splice_pipe_desc *);
+extern void splice_shrink_spd(struct splice_pipe_desc *);
extern void spd_release_page(struct splice_pipe_desc *, unsigned int);
extern const struct pipe_buf_operations page_cache_pipe_buf_ops;