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[media] saa7164: fix double fetch PCIe access condition 

Avoid a double fetch by reusing the values from the prior transfer.

Originally reported via https://bugzilla.kernel.org/show_bug.cgi?id=195559

Thanks to Pengfei Wang <wpengfeinudt@gmail.com> for reporting.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Reported-by: Pengfei Wang <wpengfeinudt@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Steven Toth 2017-06-06 09:30:27 -03:00 committed by Mauro Carvalho Chehab
parent 9e9e6a7814
commit 6fb05e0dd3
1 changed files with 1 additions and 12 deletions
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13
drivers/media/pci/saa7164/saa7164-bus.c
View File

@ -389,11 +389,11 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
msg_tmp.size = le16_to_cpu((__force __le16)msg_tmp.size);
msg_tmp.command = le32_to_cpu((__force __le32)msg_tmp.command);
msg_tmp.controlselector = le16_to_cpu((__force __le16)msg_tmp.controlselector);
memcpy(msg, &msg_tmp, sizeof(*msg));
/* No need to update the read positions, because this was a peek */
/* If the caller specifically want to peek, return */
if (peekonly) {
memcpy(msg, &msg_tmp, sizeof(*msg));
goto peekout;
}
@ -438,21 +438,15 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
space_rem = bus->m_dwSizeGetRing - curr_grp;
if (space_rem < sizeof(*msg)) {
/* msg wraps around the ring */
memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, space_rem);
memcpy_fromio((u8 *)msg + space_rem, bus->m_pdwGetRing,
sizeof(*msg) - space_rem);
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing + sizeof(*msg) -
space_rem, buf_size);
} else if (space_rem == sizeof(*msg)) {
memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing, buf_size);
} else {
/* Additional data wraps around the ring */
memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf) {
memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp +
sizeof(*msg), space_rem - sizeof(*msg));
@ -465,15 +459,10 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
} else {
/* No wrapping */
memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp + sizeof(*msg),
buf_size);
}
/* Convert from little endian to CPU */
msg->size = le16_to_cpu((__force __le16)msg->size);
msg->command = le32_to_cpu((__force __le32)msg->command);
msg->controlselector = le16_to_cpu((__force __le16)msg->controlselector);
/* Update the read positions, adjusting the ring */
saa7164_writel(bus->m_dwGetReadPos, new_grp);