Le 27/07/2020 à 18:16, Joe Perches a écrit :
On Mon, 2020-07-27 at 09:09 -0700, Joe Perches wrote:
On Mon, 2020-07-27 at 15:51 +0200, Christophe JAILLET wrote:
Avoid a memset after a call to 'dma_alloc_coherent()'.
This is useless since
commit 518a2f1925c3 ("dma-mapping: zero memory returned from dma_alloc_*")
[]
diff --git a/drivers/media/pci/bt8xx/btcx-risc.c b/drivers/media/pci/bt8xx/btcx-risc.c
[]
@@ -73,7 +73,6 @@ int btcx_riscmem_alloc(struct pci_dev *pci,
dprintk("btcx: riscmem alloc [%d] dma=%lx cpu=%p size=%d\n",
memcnt, (unsigned long)dma, cpu, size);
}
- memset(risc->cpu,0,risc->size);
return 0;
}
Likely NAK.
This is not useless as risc->cpu may be reused
and the alloc may not have been done.
Perhaps a little rewrite for clarity:
---
drivers/media/pci/bt8xx/btcx-risc.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/drivers/media/pci/bt8xx/btcx-risc.c b/drivers/media/pci/bt8xx/btcx-risc.c
index 51257980f539..311f4ca2a108 100644
--- a/drivers/media/pci/bt8xx/btcx-risc.c
+++ b/drivers/media/pci/bt8xx/btcx-risc.c
@@ -56,24 +56,26 @@ int btcx_riscmem_alloc(struct pci_dev *pci,
struct btcx_riscmem *risc,
unsigned int size)
{
- __le32 *cpu;
- dma_addr_t dma = 0;
-
- if (NULL != risc->cpu && risc->size < size)
- btcx_riscmem_free(pci,risc);
- if (NULL == risc->cpu) {
- cpu = pci_alloc_consistent(pci, size, &dma);
- if (NULL == cpu)
+ if (risc->cpu && risc->size < size)
+ btcx_riscmem_free(pci, risc);
+
+ if (risc->cpu) {
+ memset(risc->cpu, 0, risc->size);
+ } else {
+ dma_addr_t dma = 0;
+
+ risc->cpu = pci_alloc_consistent(pci, size, &dma);
+ if (!risc->cpu)
return -ENOMEM;
- risc->cpu = cpu;
+
risc->dma = dma;
risc->size = size;
memcnt++;
dprintk("btcx: riscmem alloc [%d] dma=%lx cpu=%p size=%d\n",
- memcnt, (unsigned long)dma, cpu, size);
+ memcnt, (unsigned long)dma, risc->cpu, size);
}
- memset(risc->cpu,0,risc->size);
+
return 0;
}
Looks good to me.
Just note, that this will not apply after patch 1/2 is applied, because
it turns pci_alloc_consistent() into dma_alloc_coherent().
CJ
