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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2007-02-05 21:18:19 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2007-02-05 21:18:19 +0100 |
| commit | d54853ef8cb17296ac7bce9c77430fb7c80532d0 (patch) | |
| tree | 649e14d532e17231225a042a7c9a3d9207ad91ee /drivers/s390/block/dasd.c | |
| parent | [S390] noexec protection (diff) | |
| download | linux-d54853ef8cb17296ac7bce9c77430fb7c80532d0.tar.xz linux-d54853ef8cb17296ac7bce9c77430fb7c80532d0.zip | |
[S390] ETR support.
This patch adds support for clock synchronization to an external time
reference (ETR). The external time reference sends an oscillator
signal and a synchronization signal every 2^20 microseconds to keep
the TOD clocks of all connected servers in sync. For availability
two ETR units can be connected to a machine. If the clock deviates
for more than the sync-check tolerance all cpus get a machine check
that indicates that the clock is out of sync. For the lovely details
how to get the clock back in sync see the code below.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/block/dasd.c')
| -rw-r--r-- | drivers/s390/block/dasd.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index f208940c463c..555e18a6b781 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -1232,6 +1232,19 @@ __dasd_process_blk_queue(struct dasd_device * device) if (IS_ERR(cqr)) { if (PTR_ERR(cqr) == -ENOMEM) break; /* terminate request queue loop */ + if (PTR_ERR(cqr) == -EAGAIN) { + /* + * The current request cannot be build right + * now, we have to try later. If this request + * is the head-of-queue we stop the device + * for 1/2 second. + */ + if (!list_empty(&device->ccw_queue)) + break; + device->stopped |= DASD_STOPPED_PENDING; + dasd_set_timer(device, HZ/2); + break; + } DBF_DEV_EVENT(DBF_ERR, device, "CCW creation failed (rc=%ld) " "on request %p", |