On systems employing the "lazy loop device removal",
kernel commit commit a1ecac3b0656a68259927c234e505804d33a7b83
("loop: Make explicit loop device destruction lazy"),
ioctl(LOOP_CLR_FD) may return 0 when the loop device is in use,
for example by udev.
Therefore, there is a chance that a quick attach/detach may not
give udev enough time to complete, like this:
open("file.img", O_RDWR) = 4
ioctl(3, LOOP_SET_FD, 0x4) = 0
close(3) = 0
close(4) = 0
open("/dev/loop0", O_RDONLY) = 3
ioctl(3, LOOP_CLR_FD, 0) = 0
close(3) = 0
open("/dev/loop0", O_RDWR) = 3
open("file.img", O_RDWR) = 4
ioctl(3, LOOP_SET_FD, 0x4) = -1 EBUSY (Device or resource busy)
So let's wait until the kernel frees the loop device, i.e.
when ioctl(LOOP_CLR_FD) starts failing with ENXIO.
Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmansk...@oracle.com>
---
lib/tst_device.c | 17 ++++++-----------
1 files changed, 6 insertions(+), 11 deletions(-)
diff --git a/lib/tst_device.c b/lib/tst_device.c
index 3bded53..9a92fc8 100644
--- a/lib/tst_device.c
+++ b/lib/tst_device.c
@@ -150,30 +150,25 @@ static void attach_device(void (*cleanup_fn)(void),
static void detach_device(void (*cleanup_fn)(void), const char *dev)
{
- int dev_fd, err, i;
+ int dev_fd, ret, i;
dev_fd = SAFE_OPEN(cleanup_fn, dev, O_RDONLY);
- /* keep trying to clear LOOPDEV fd if EBUSY, a quick succession
+ /* keep trying to clear LOOPDEV until we get ENXIO, a quick succession
* of attach/detach might not give udev enough time to complete */
for (i = 0; i < 40; i++) {
- if (ioctl(dev_fd, LOOP_CLR_FD, 0) == 0) {
+ ret = ioctl(dev_fd, LOOP_CLR_FD, 0);
+
+ if (ret && (errno == ENXIO)) {
close(dev_fd);
return;
}
- if (errno != EBUSY) {
- err = errno;
- close(dev_fd);
- tst_brkm(TBROK, cleanup_fn,
- "ioctl(%s, LOOP_CLR_FD, 0) failed: %s",
- dev, tst_strerrno(err));
- }
usleep(50000);
}
close(dev_fd);
tst_brkm(TBROK, cleanup_fn,
- "ioctl(%s, LOOP_CLR_FD, 0) EBUSY for too long", dev);
+ "ioctl(%s, LOOP_CLR_FD, 0) no ENXIO for too long", dev);
}
const char *tst_acquire_device(void (cleanup_fn)(void))
--
1.7.1
------------------------------------------------------------------------------
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