[igt-dev] [PATCH] igt_kmod: handle EPIPE on kmsg

[Lucas De Marchi]

If kmsg rotates due to a huge log, the read() will fail with EPIPE since
the seek() we did is not valid anymore. When we get an EPIPE, the kernel
will set our pointer to the last entry available, so just retry another
read.

Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---
 lib/igt_kmod.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/igt_kmod.c b/lib/igt_kmod.c
index 01faca39..c3da4667 100644
--- a/lib/igt_kmod.c
+++ b/lib/igt_kmod.c
@@ -391,8 +391,15 @@ static void kmsg_dump(int fd)
 		if (r < 0) {
 			if (errno == EINTR)
 				continue;
+
+			if (errno == EPIPE) {
+				igt_warn("kmsg truncated: too many messages. You may want to increase log_buf_len in kmcdline\n");
+				continue;
+			}
+
 			if (errno != EAGAIN)
-				igt_warn("kmsg truncated due to unknown error: %m\n");
+				igt_warn("kmsg truncated: unknown error (%m)\n");
+
 			break;
 		}
 
-- 
2.23.0