[CRIU] [PATCH] net/sysctl: silence read error in case of CTL_FLAGS_READ_EIO_SKIP

[Pavel Tikhomirov]

Because stable_secret sysctl c/r produces a lot of spam error messages
in tests: https://github.com/xemul/criu/issues/160 But EIO for these
sysctl is valid behavior and no error need to be printed.

More general solution will also silence error messages for
sysctl_read_{u32,s32,u64}, but the flag CTL_FLAGS_READ_EIO_SKIP is
now used only for __CTL_STR and only for stable_secret so we can do
silence error only in sysctl_read_char.

Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 criu/sysctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/criu/sysctl.c b/criu/sysctl.c
index a38fcb8..77d9bda 100644
--- a/criu/sysctl.c
+++ b/criu/sysctl.c
@@ -132,7 +132,8 @@ sysctl_read_char(int fd, struct sysctl_req *req, char *arg, int nr)
 	pr_debug("%s nr %d\n", req->name, nr);
 	ret = read(fd, arg, nr);
 	if (ret < 0) {
-		pr_perror("Can't read %s", req->name);
+		if (errno != EIO ||  !(req->flags & CTL_FLAGS_READ_EIO_SKIP))
+			pr_perror("Can't read %s", req->name);
 		goto err;
 	}
 	ret = 0;
-- 
2.5.5