From: Stefan Haberland Date: Tue, 6 Oct 2009 08:34:15 +0000 (+0200) Subject: [S390] dasd: fix race condition in resume code X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6fca97a958bc3c67566aa91eafc6a5be2e66d6b3;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git [S390] dasd: fix race condition in resume code There is a race while re-reading the device characteristics. After cleaning the memory area a cqr is build which reads the device characteristics. This may take a rather long time and the device characteristics structure is zero during this. Now it could be possible that the block tasklet starts working and a new cqr will be build. The build_cp command refers to the device characteristics structure and this may lead into a divide by zero exception. Fix this by re-reading the device characteristics into a temporary structur and copy the data to the original structure. Also take the ccwdev_lock. Signed-off-by: Stefan Haberland Signed-off-by: Martin Schwidefsky --- diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c index dad0449475b6..53b8c255360a 100644 --- a/drivers/s390/block/dasd.c +++ b/drivers/s390/block/dasd.c @@ -2508,8 +2508,6 @@ int dasd_generic_restore_device(struct ccw_device *cdev) device->stopped &= ~DASD_UNRESUMED_PM; dasd_schedule_device_bh(device); - if (device->block) - dasd_schedule_block_bh(device->block); if (device->discipline->restore) rc = device->discipline->restore(device); @@ -2520,6 +2518,9 @@ int dasd_generic_restore_device(struct ccw_device *cdev) */ device->stopped |= DASD_UNRESUMED_PM; + if (device->block) + dasd_schedule_block_bh(device->block); + dasd_put_device(device); return 0; } diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index ab3521755588..0be7c15f45c5 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -2338,6 +2338,8 @@ static struct dasd_ccw_req *dasd_eckd_build_cp(struct dasd_device *startdev, /* Calculate number of blocks/records per track. */ blksize = block->bp_block; blk_per_trk = recs_per_track(&private->rdc_data, 0, blksize); + if (blk_per_trk == 0) + return ERR_PTR(-EINVAL); /* Calculate record id of first and last block. */ first_rec = first_trk = blk_rq_pos(req) >> block->s2b_shift; first_offs = sector_div(first_trk, blk_per_trk); @@ -3211,6 +3213,7 @@ int dasd_eckd_pm_freeze(struct dasd_device *device) int dasd_eckd_restore_device(struct dasd_device *device) { struct dasd_eckd_private *private; + struct dasd_eckd_characteristics temp_rdc_data; int is_known, rc; struct dasd_uid temp_uid; @@ -3245,15 +3248,17 @@ int dasd_eckd_restore_device(struct dasd_device *device) dasd_eckd_read_features(device); /* Read Device Characteristics */ - memset(&private->rdc_data, 0, sizeof(private->rdc_data)); rc = dasd_generic_read_dev_chars(device, DASD_ECKD_MAGIC, - &private->rdc_data, 64); + &temp_rdc_data, 64); if (rc) { DBF_EVENT(DBF_WARNING, "Read device characteristics failed, rc=%d for " "device: %s", rc, dev_name(&device->cdev->dev)); goto out_err; } + spin_lock(get_ccwdev_lock(device->cdev)); + memcpy(&private->rdc_data, &temp_rdc_data, sizeof(temp_rdc_data)); + spin_unlock(get_ccwdev_lock(device->cdev)); /* add device to alias management */ dasd_alias_add_device(device);