relay: fix bogus cast in subbuf_splice_actor()
PATCH 1/1 relay: fix bogus cast in subbuf_splice_actor()
The current code that sets the read position in subbuf_splice_actor may give erroneous results if the buffer size isn't a power of 2. This patch fixes the problem.
Signed-off-by Tom Zanussi <[email protected]>
--- relay.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
kernel/relay.c +3 -1
@@ -1074,7 +1074,9 @@ static int subbuf_splice_actor(struct file *in,unsigned int pidx, poff, total_len, subbuf_pages, ret;struct rchan_buf *rbuf = in->private_data;unsigned int subbuf_size = rbuf->chan->subbuf_size; -size_t read_start = ((size_t )*ppos) % rbuf->chan->alloc_size; +uint64_t pos = (uint64_t ) *ppos; +uint32_t alloc_size = (uint32_t ) rbuf->chan->alloc_size; +size_t read_start = (size_t )do_div (pos, alloc_size);size_t read_subbuf = read_start / subbuf_size;size_t padding = rbuf->padding[read_subbuf];size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
Quoted 3 lines · Tom Zanussi
The current code that sets the read position in
subbuf_splice_actormay give erroneous results if the buffer size isn't a power of 2. This patch fixes the problem.
Thanks Tom, I just added this for my upstream branch, if you submit it directly first, I'll just rebase without it again. Otherwise it'll go in when I ask Linus to pull next.
Signature · 1 line
Jens Axboe