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Subject[PATCH] firewire: Add dummy read_csr/write_csr functions
Date
This fixes segfaults when a card gets yanked off of the PCIe bus while
busy, e.g. with a userspace app trying to get the cycle time:

[8638860.994310] Call Trace:
[8638860.994313] ioctl_get_cycle_timer2+0x4f/0xd0 [firewire_core]
[8638860.994323] fw_device_op_ioctl+0xae/0x150 [firewire_core]
[8638860.994328] __x64_sys_ioctl+0x7d/0xb0
[8638860.994332] do_syscall_64+0x45/0x80
[8638860.994337] entry_SYSCALL_64_after_hwframe+0x44/0xae

Signed-off-by: Hector Martin <marcan@marcan.st>
---
drivers/firewire/core-card.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 54be88167c60..d994da6cf465 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -616,6 +616,15 @@ static struct fw_iso_context *dummy_allocate_iso_context(struct fw_card *card,
return ERR_PTR(-ENODEV);
}

+static u32 dummy_read_csr(struct fw_card *card, int csr_offset)
+{
+ return 0;
+}
+
+static void dummy_write_csr(struct fw_card *card, int csr_offset, u32 value)
+{
+}
+
static int dummy_start_iso(struct fw_iso_context *ctx,
s32 cycle, u32 sync, u32 tags)
{
@@ -649,6 +658,8 @@ static const struct fw_card_driver dummy_driver_template = {
.send_response = dummy_send_response,
.cancel_packet = dummy_cancel_packet,
.enable_phys_dma = dummy_enable_phys_dma,
+ .read_csr = dummy_read_csr,
+ .write_csr = dummy_write_csr,
.allocate_iso_context = dummy_allocate_iso_context,
.start_iso = dummy_start_iso,
.set_iso_channels = dummy_set_iso_channels,
--
2.33.0
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