Messages in this thread Patch in this message | | | Date | Wed, 22 Jun 2022 15:12:32 +0200 | Subject | Re: [PATCH] media: dvb_ringbuffer : Fix a bug in dvb_ringbuffer.c | From | Hans Petter Selasky <> |
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Hi Kieran,
The consumed variable should not be negative. This bug has been there since the beginning of the GIT at Linux from what I can see.
+1
--HPS
From 108c6acb2cc4bc4314b96f6f254a04b2873a096c Mon Sep 17 00:00:00 2001 From: YongSu Yoo <yongsuyoo0215@gmail.com> Date: Sun, 22 May 2022 04:53:12 +0000 Subject: [PATCH] media: dvb_ringbuffer : Fix a bug in dvb_ringbuffer.c
Signed-off-by:Yongsu Yoo <yongsuyoo0215@gmail.com>
The function dvb_ringbuffer_pkt_next in /linux-next/drviers/media/dvb-core/dvb_ringbuffer.c, which searches the idx of the next valid packet in the ring buffer of the ca->slot_info[slot].rx_buffer at /linux-next/drivers/media/dvb-core/dvb_ca_en50221.c, has the following problem. In calculating the amounts of the consumed address of the ring buffer, if the read address(rbuf->pread) of the ring buffer is smaller than the idx, the amounts of the searched address should be (idx - rbuf->pread), whereas if the read address(rbuf->pread) of the ring buffer is larger than the idx, the amounts of the consumed address should be (idx - rbuf->pread + rbug->size). But there exists an incorrect logic that the rbug-size was not properly added on (idx - rbug->pread) in the later case. With this commit, we fixed this bug. --- drivers/media/dvb-core/dvb_ringbuffer.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/media/dvb-core/dvb_ringbuffer.c b/drivers/media/dvb-core/dvb_ringbuffer.c index d1d471af0636..7d4558de8e83 100644 --- a/drivers/media/dvb-core/dvb_ringbuffer.c +++ b/drivers/media/dvb-core/dvb_ringbuffer.c @@ -335,7 +335,9 @@ ssize_t dvb_ringbuffer_pkt_next(struct dvb_ringbuffer *rbuf, size_t idx, size_t* idx = (idx + curpktlen + DVB_RINGBUFFER_PKTHDRSIZE) % rbuf->size; }
- consumed = (idx - rbuf->pread) % rbuf->size; + consumed = (idx - rbuf->pread); + if (consumed < 0) + consumed += rbuf->size;
while((dvb_ringbuffer_avail(rbuf) - consumed) > DVB_RINGBUFFER_PKTHDRSIZE) {
-- 2.17.1
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