If system continues to produce log entries, test_read_block()
may never end, because it won't reach EOF neither timeout.
This has been observed with x38_edac in debug kernel, where
this module keeps producing periodic log entries.
The test already has a timeout on single read, this patch
adds overall timeout for all reads combined to not cross
over specified value. This should prevent testcase from
running in infinite loop in case log entries are generated
periodically / indefinitely.
It also adds seek to end of kmsg for block/nonblock read tests
as it is not necessary to go through whole content entry by entry.
Signed-off-by: Jan Stancek <jstan...@redhat.com>
---
testcases/kernel/logging/kmsg/kmsg01.c | 36 ++++++++++++++++++++++++++++------
1 file changed, 30 insertions(+), 6 deletions(-)
diff --git a/testcases/kernel/logging/kmsg/kmsg01.c
b/testcases/kernel/logging/kmsg/kmsg01.c
index 4e24298..4307947 100644
--- a/testcases/kernel/logging/kmsg/kmsg01.c
+++ b/testcases/kernel/logging/kmsg/kmsg01.c
@@ -52,7 +52,8 @@
#define NUM_READ_MSGS 3
#define NUM_READ_RETRY 10
#define NUM_OVERWRITE_MSGS 1024
-#define READ_TIMEOUT 5
+#define SINGLE_READ_TIMEOUT 2
+#define READ_TIMEOUT_MS (30*1000)
char *TCID = "kmsg01";
static void setup(void);
@@ -196,11 +197,12 @@ static int timed_read(int fd, int timeout_sec)
* -1 on read error, errno reflects read() errno
* -2 on timeout
*/
-static int timed_read_kmsg(int fd, int timeout_sec)
+static int timed_read_kmsg(int fd, int timeout_ms)
{
int child, status, ret = 0;
int pipefd[2];
char msg[MAX_MSGSIZE];
+ long long elapsed_ms = 0;
if (pipe(pipefd) != 0)
tst_brkm(TBROK|TERRNO, cleanup, "pipe failed");
@@ -231,11 +233,22 @@ static int timed_read_kmsg(int fd, int timeout_sec)
SAFE_CLOSE(cleanup, pipefd[1]);
/* parent reads pipe until it reaches eof or until read times out */
+ tst_timer_start(CLOCK_MONOTONIC);
do {
- TEST(timed_read(pipefd[0], timeout_sec));
- } while (TEST_RETURN > 0);
+ TEST(timed_read(pipefd[0], SINGLE_READ_TIMEOUT));
+ tst_timer_stop();
+ elapsed_ms = tst_timer_elapsed_ms();
+ } while (TEST_RETURN > 0 && elapsed_ms < timeout_ms);
SAFE_CLOSE(cleanup, pipefd[0]);
+ if (elapsed_ms >= timeout_ms) {
+ /* this is not necessarily error, kernel or user-space
+ * process may generate messages at higher rate than what
+ * we would consider as 'blocked', see SINGLE_READ_TIMEOUT */
+ tst_resm(TWARN, "reads taking too long, giving up");
+ TEST_RETURN = -2;
+ }
+
/* child is blocked, kill it */
if (TEST_RETURN == -2)
kill(child, SIGTERM);
@@ -261,7 +274,12 @@ static void test_read_nonblock(void)
if (fd < 0)
tst_brkm(TBROK|TERRNO, cleanup, "failed to open /dev/kmsg");
- TEST(timed_read_kmsg(fd, READ_TIMEOUT));
+ if (lseek(fd, 0, SEEK_END) == -1)
+ tst_resm(TFAIL|TERRNO, "SEEK_END 0 failed");
+
+ /* /dev/kmsg opened with O_NONBLOCK will return EAGAIN when
+ * no more records are available */
+ TEST(timed_read_kmsg(fd, READ_TIMEOUT_MS));
if (TEST_RETURN == -1 && TEST_ERRNO == EAGAIN)
tst_resm(TPASS, "non-block read returned EAGAIN");
else
@@ -279,7 +297,12 @@ static void test_read_block(void)
if (fd < 0)
tst_brkm(TBROK|TERRNO, cleanup, "failed to open /dev/kmsg");
- TEST(timed_read_kmsg(fd, READ_TIMEOUT));
+ if (lseek(fd, 0, SEEK_END) == -1)
+ tst_resm(TFAIL|TERRNO, "SEEK_END 0 failed");
+
+ /* /dev/kmsg opened without O_NONBLOCK will block on read when
+ * no more records are available */
+ TEST(timed_read_kmsg(fd, READ_TIMEOUT_MS));
if (TEST_RETURN == -2)
tst_resm(TPASS, "read blocked");
else
@@ -582,6 +605,7 @@ static void setup(void)
if (tst_kvercmp(3, 5, 0) < 0)
tst_brkm(TCONF, NULL, "This test requires kernel"
" >= 3.5.0");
+ tst_timer_check(CLOCK_MONOTONIC);
srand(getpid());
TEST_PAUSE;
}
--
1.8.3.1
------------------------------------------------------------------------------
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