diff options
Diffstat (limited to 'drivers/scsi/scsi_scan.c')
| -rw-r--r-- | drivers/scsi/scsi_scan.c | 203 |
1 files changed, 197 insertions, 6 deletions
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 94a274645f6f..aa1b1e0e9d22 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -29,7 +29,9 @@ #include <linux/moduleparam.h> #include <linux/init.h> #include <linux/blkdev.h> -#include <asm/semaphore.h> +#include <linux/delay.h> +#include <linux/kthread.h> +#include <linux/spinlock.h> #include <scsi/scsi.h> #include <scsi/scsi_cmnd.h> @@ -87,6 +89,11 @@ module_param_named(max_luns, max_scsi_luns, int, S_IRUGO|S_IWUSR); MODULE_PARM_DESC(max_luns, "last scsi LUN (should be between 1 and 2^32-1)"); +static char scsi_scan_type[6] = "sync"; + +module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type), S_IRUGO); +MODULE_PARM_DESC(scan, "sync, async or none"); + /* * max_scsi_report_luns: the maximum number of LUNS that will be * returned from the REPORT LUNS command. 8 times this value must @@ -108,6 +115,68 @@ MODULE_PARM_DESC(inq_timeout, "Timeout (in seconds) waiting for devices to answer INQUIRY." " Default is 5. Some non-compliant devices need more."); +static DEFINE_SPINLOCK(async_scan_lock); +static LIST_HEAD(scanning_hosts); + +struct async_scan_data { + struct list_head list; + struct Scsi_Host *shost; + struct completion prev_finished; +}; + +/** + * scsi_complete_async_scans - Wait for asynchronous scans to complete + * + * Asynchronous scans add themselves to the scanning_hosts list. Once + * that list is empty, we know that the scans are complete. Rather than + * waking up periodically to check the state of the list, we pretend to be + * a scanning task by adding ourselves at the end of the list and going to + * sleep. When the task before us wakes us up, we take ourselves off the + * list and return. + */ +int scsi_complete_async_scans(void) +{ + struct async_scan_data *data; + + do { + if (list_empty(&scanning_hosts)) + return 0; + /* If we can't get memory immediately, that's OK. Just + * sleep a little. Even if we never get memory, the async + * scans will finish eventually. + */ + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + msleep(1); + } while (!data); + + data->shost = NULL; + init_completion(&data->prev_finished); + + spin_lock(&async_scan_lock); + /* Check that there's still somebody else on the list */ + if (list_empty(&scanning_hosts)) + goto done; + list_add_tail(&data->list, &scanning_hosts); + spin_unlock(&async_scan_lock); + + printk(KERN_INFO "scsi: waiting for bus probes to complete ...\n"); + wait_for_completion(&data->prev_finished); + + spin_lock(&async_scan_lock); + list_del(&data->list); + done: + spin_unlock(&async_scan_lock); + + kfree(data); + return 0; +} + +#ifdef MODULE +/* Only exported for the benefit of scsi_wait_scan */ +EXPORT_SYMBOL_GPL(scsi_complete_async_scans); +#endif + /** * scsi_unlock_floptical - unlock device via a special MODE SENSE command * @sdev: scsi device to send command to @@ -619,7 +688,7 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result, * SCSI_SCAN_LUN_PRESENT: a new scsi_device was allocated and initialized **/ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result, - int *bflags) + int *bflags, int async) { /* * XXX do not save the inquiry, since it can change underneath us, @@ -805,7 +874,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result, * register it and tell the rest of the kernel * about it. */ - if (scsi_sysfs_add_sdev(sdev) != 0) + if (!async && scsi_sysfs_add_sdev(sdev) != 0) return SCSI_SCAN_NO_RESPONSE; return SCSI_SCAN_LUN_PRESENT; @@ -974,7 +1043,7 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget, goto out_free_result; } - res = scsi_add_lun(sdev, result, &bflags); + res = scsi_add_lun(sdev, result, &bflags, shost->async_scan); if (res == SCSI_SCAN_LUN_PRESENT) { if (bflags & BLIST_KEY) { sdev->lockable = 0; @@ -1474,6 +1543,9 @@ void scsi_scan_target(struct device *parent, unsigned int channel, { struct Scsi_Host *shost = dev_to_shost(parent); + if (!shost->async_scan) + scsi_complete_async_scans(); + mutex_lock(&shost->scan_mutex); if (scsi_host_scan_allowed(shost)) __scsi_scan_target(parent, channel, id, lun, rescan); @@ -1519,6 +1591,9 @@ int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel, "%s: <%u:%u:%u>\n", __FUNCTION__, channel, id, lun)); + if (!shost->async_scan) + scsi_complete_async_scans(); + if (((channel != SCAN_WILD_CARD) && (channel > shost->max_channel)) || ((id != SCAN_WILD_CARD) && (id >= shost->max_id)) || ((lun != SCAN_WILD_CARD) && (lun > shost->max_lun))) @@ -1539,14 +1614,130 @@ int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel, return 0; } +static void scsi_sysfs_add_devices(struct Scsi_Host *shost) +{ + struct scsi_device *sdev; + shost_for_each_device(sdev, shost) { + if (scsi_sysfs_add_sdev(sdev) != 0) + scsi_destroy_sdev(sdev); + } +} + +/** + * scsi_prep_async_scan - prepare for an async scan + * @shost: the host which will be scanned + * Returns: a cookie to be passed to scsi_finish_async_scan() + * + * Tells the midlayer this host is going to do an asynchronous scan. + * It reserves the host's position in the scanning list and ensures + * that other asynchronous scans started after this one won't affect the + * ordering of the discovered devices. + */ +struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) +{ + struct async_scan_data *data; + + if (strncmp(scsi_scan_type, "sync", 4) == 0) + return NULL; + + if (shost->async_scan) { + printk("%s called twice for host %d", __FUNCTION__, + shost->host_no); + dump_stack(); + return NULL; + } + + data = kmalloc(sizeof(*data), GFP_KERNEL); + if (!data) + goto err; + data->shost = scsi_host_get(shost); + if (!data->shost) + goto err; + init_completion(&data->prev_finished); + + spin_lock(&async_scan_lock); + shost->async_scan = 1; + if (list_empty(&scanning_hosts)) + complete(&data->prev_finished); + list_add_tail(&data->list, &scanning_hosts); + spin_unlock(&async_scan_lock); + + return data; + + err: + kfree(data); + return NULL; +} + +/** + * scsi_finish_async_scan - asynchronous scan has finished + * @data: cookie returned from earlier call to scsi_prep_async_scan() + * + * All the devices currently attached to this host have been found. + * This function announces all the devices it has found to the rest + * of the system. + */ +void scsi_finish_async_scan(struct async_scan_data *data) +{ + struct Scsi_Host *shost; + + if (!data) + return; + + shost = data->shost; + if (!shost->async_scan) { + printk("%s called twice for host %d", __FUNCTION__, + shost->host_no); + dump_stack(); + return; + } + + wait_for_completion(&data->prev_finished); + + scsi_sysfs_add_devices(shost); + + spin_lock(&async_scan_lock); + shost->async_scan = 0; + list_del(&data->list); + if (!list_empty(&scanning_hosts)) { + struct async_scan_data *next = list_entry(scanning_hosts.next, + struct async_scan_data, list); + complete(&next->prev_finished); + } + spin_unlock(&async_scan_lock); + + scsi_host_put(shost); + kfree(data); +} + +static int do_scan_async(void *_data) +{ + struct async_scan_data *data = _data; + scsi_scan_host_selected(data->shost, SCAN_WILD_CARD, SCAN_WILD_CARD, + SCAN_WILD_CARD, 0); + + scsi_finish_async_scan(data); + return 0; +} + /** * scsi_scan_host - scan the given adapter * @shost: adapter to scan **/ void scsi_scan_host(struct Scsi_Host *shost) { - scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD, - SCAN_WILD_CARD, 0); + struct async_scan_data *data; + + if (strncmp(scsi_scan_type, "none", 4) == 0) + return; + + data = scsi_prep_async_scan(shost); + if (!data) { + scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD, + SCAN_WILD_CARD, 0); + return; + } + kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no); } EXPORT_SYMBOL(scsi_scan_host); |