In commit 5cd8d46e a fix was applied for data corruption in
tpacket_snd. A selftest was added in commit 358be656 which
validates this fix.
Unfortunately this bug still persists, although since this fix less
likely to trigger. This bug was initially observed using a PACKET_MMAP
application, but can also be seen by tweaking the kernel selftest.
By tweaking the selftest txring_overwrite.c to run
as an infinite loop, the data corruption will still trigger. It
seems to occur faster by generating interrupts (e.g. by plugging
in USB devices). Tested with kernel version 5.2-RC7.
Cause for this bug is still unclear.
Signed-off-by: Frank de Brabander <debraban...@gmail.com>
---
tools/testing/selftests/net/txring_overwrite.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/net/txring_overwrite.c
b/tools/testing/selftests/net/txring_overwrite.c
index fd8b1c6..3ee23e5 100644
--- a/tools/testing/selftests/net/txring_overwrite.c
+++ b/tools/testing/selftests/net/txring_overwrite.c
@@ -143,19 +143,22 @@ static int read_verify_pkt(int fdr, char payload_char)
int ret;
ret = read(fdr, buf, sizeof(buf));
- if (ret != sizeof(buf))
- error(1, errno, "read");
+ if (ret != sizeof(buf)) {
+ //error(1, errno, "read");
+ printf("read error\n");
+ return 1;
+ }
if (buf[60] != payload_char) {
printf("wrong pattern: 0x%x != 0x%x\n", buf[60], payload_char);
return 1;
}
- printf("read: %c (0x%x)\n", buf[60], buf[60]);
+ //printf("read: %c (0x%x)\n", buf[60], buf[60]);
return 0;
}
-int main(int argc, char **argv)
+void run_test(void)
{
const char payload_patterns[] = "ab";
char *ring;
@@ -177,3 +180,10 @@ int main(int argc, char **argv)
return ret;
}
+
+int main(int argc, char **argv)
+{
+ while (true) {
+ run_test();
+ }
+}
--
2.7.4
