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| author | Duncan Sands <duncan.sands@math.u-psud.fr> | 2006-04-11 10:18:57 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@infradead.org> | 2006-05-12 19:54:50 -0300 |
| commit | bba3ad76a82eb458d31b136fa2414216e20c99cc (patch) | |
| tree | 3b727a066fe78d7c88cf08c633d4b3887b0e1f37 | |
| parent | 9175b8544ff7b73b158df370acc1d828b28b80b7 (diff) | |
| download | blackbird-op-linux-bba3ad76a82eb458d31b136fa2414216e20c99cc.tar.gz blackbird-op-linux-bba3ad76a82eb458d31b136fa2414216e20c99cc.zip | |
V4L/DVB (3766): Correct buffer size calculations in cx88-core.c
The computation in cx88_risc_buffer suffers from the mistake:
a non-zero padding value can cause more page borders to be crossed,
leading to big buffer over-runs.
This patch changes the additive constant from 3 + 4 to 4
It also changees the constant in cx88_risc_databuffer from 3 + 4 to 2,
because 2 dwords are the correct vaule.
Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
| -rw-r--r-- | drivers/media/video/cx88/cx88-core.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/drivers/media/video/cx88/cx88-core.c b/drivers/media/video/cx88/cx88-core.c index 2c3d9f1999be..e1092d5d4628 100644 --- a/drivers/media/video/cx88/cx88-core.c +++ b/drivers/media/video/cx88/cx88-core.c @@ -146,9 +146,11 @@ int cx88_risc_buffer(struct pci_dev *pci, struct btcx_riscmem *risc, fields++; /* estimate risc mem: worst case is one write per page border + - one write per scan line + syncs + jump (all 2 dwords) */ - instructions = (bpl * lines * fields) / PAGE_SIZE + lines * fields; - instructions += 3 + 4; + one write per scan line + syncs + jump (all 2 dwords). Padding + can cause next bpl to start close to a page border. First DMA + region may be smaller than PAGE_SIZE */ + instructions = fields * (1 + ((bpl + padding) * lines) / PAGE_SIZE + lines); + instructions += 2; if ((rc = btcx_riscmem_alloc(pci,risc,instructions*8)) < 0) return rc; @@ -176,9 +178,11 @@ int cx88_risc_databuffer(struct pci_dev *pci, struct btcx_riscmem *risc, int rc; /* estimate risc mem: worst case is one write per page border + - one write per scan line + syncs + jump (all 2 dwords) */ - instructions = (bpl * lines) / PAGE_SIZE + lines; - instructions += 3 + 4; + one write per scan line + syncs + jump (all 2 dwords). Here + there is no padding and no sync. First DMA region may be smaller + than PAGE_SIZE */ + instructions = 1 + (bpl * lines) / PAGE_SIZE + lines; + instructions += 1; if ((rc = btcx_riscmem_alloc(pci,risc,instructions*8)) < 0) return rc; |
