21.07.05 Luke Kosewski * A patch to add a general-purpose hotswap framework to libata. From the point of view of the driver writer, we only have two new API functions; 'ata_hotplug_plug' and 'ata_hotplug_unplug', which have rather self-explanatory functions. * A few misc changes are necessary to properly reset flags which are set by devices when they are present to make sure that new devices (for instance, disks with different max UDMA transfer rates, not using LBA48, etc.) being swapped in do not assume values for the old devices. * Gratuitous comments here that can probably be removed, so that anyone looking at this can understand this and poke holes in my logic. Signed-off-by: Luke Kosewski --- linux-2.6.13-rc3/drivers/scsi/libata-core.c.old 2005-07-21 13:35:31.609832324 -0400 +++ linux-2.6.13-rc3/drivers/scsi/libata-core.c 2005-07-21 13:42:53.945386060 -0400 @@ -44,7 +44,6 @@ #include #include #include -#include #include #include "libata.h" @@ -65,6 +64,7 @@ static void __ata_qc_complete(struct ata static unsigned int ata_unique_id = 1; static struct workqueue_struct *ata_wq; +static struct workqueue_struct *ata_irq_wq; MODULE_AUTHOR("Jeff Garzik"); MODULE_DESCRIPTION("Library module for ATA devices"); @@ -1134,6 +1134,11 @@ static void ata_dev_identify(struct ata_ return; } + /* Necessary if we had an LBA48 drive in, we pulled it out, and put in + * a non-LBA48 drive to replace it. + */ + dev->flags &= ~ATA_DFLAG_LBA48; + if (ap->flags & (ATA_FLAG_SRST | ATA_FLAG_SATA_RESET)) using_edd = 0; else @@ -3635,6 +3640,73 @@ idle_irq: return 0; /* irq not handled */ } +void ata_check_kill_qc(struct ata_port *ap) +{ + struct ata_queued_cmd *qc = ata_qc_from_tag(ap, ap->active_tag); + + if (unlikely(qc)) { + /* This is SO bad. But we can't just run + * ata_qc_complete without doing this, because + * ata_scsi_qc_complete wants to talk to the device, + * and we can't let it do that since it doesn't exist + * anymore. + */ + ata_scsi_prepare_qc_abort(qc); + ata_qc_complete(qc, ATA_ERR); + } +} + +static void ata_hotplug_unplug_func(void *_data) +{ + struct ata_port *ap = (struct ata_port *)_data; + DPRINTK("Got an unplug request on port %d\n", ap->id); + + down(&ap->hotplug_mutex); + + ata_scsi_handle_unplug(ap); + + up(&ap->hotplug_mutex); +} + +static void ata_hotplug_plug_func(void *_data) +{ + struct ata_port *ap = (struct ata_port *)_data; + DPRINTK("Got a plug request on port %d\n", ap->id); + + down(&ap->hotplug_mutex); + /* Pure evil. Suppose that you have an 'unplug' waiting on your + * queue, and this function executes while it's there (because + * you unplugged/plugged in a disk on an SMP system VERY FAST). + * REALLY bad news, because when you unplugged your disk, you + * might have had a pending qc which will now sit there and time + * out like the mofo it is. Check to see if we have one sitting + * around and KILL IT if this is so. + */ + ata_check_kill_qc(ap); + // Observed necessary on some Seagate drives. + ap->flags |= ATA_FLAG_SATA_RESET; + ap->udma_mask = ap->orig_udma_mask; + + if (ata_bus_probe(ap) /* Does its own locking */) + ata_scsi_handle_unplug(ap); //might be necessary on SMP + else + ata_scsi_handle_plug(ap); + up(&ap->hotplug_mutex); +} + +/* Should be protected by host_set->lock */ +void ata_hotplug_unplug(struct ata_port *ap) +{ + ata_port_disable(ap); //disable this NOW, device is gone + queue_work(ata_irq_wq, &ap->hotplug_unplug_task); +} + +/* Should be protected by host_set->lock */ +void ata_hotplug_plug(struct ata_port *ap) +{ + queue_work(ata_irq_wq, &ap->hotplug_plug_task); +} + /** * ata_interrupt - Default ATA host interrupt handler * @irq: irq line (unused) @@ -3860,7 +3932,11 @@ static void ata_host_init(struct ata_por ap->cbl = ATA_CBL_NONE; ap->active_tag = ATA_TAG_POISON; ap->last_ctl = 0xFF; + ap->orig_udma_mask = ent->udma_mask; + init_MUTEX(&ap->hotplug_mutex); + INIT_WORK(&ap->hotplug_plug_task, ata_hotplug_plug_func, ap); + INIT_WORK(&ap->hotplug_unplug_task, ata_hotplug_unplug_func, ap); INIT_WORK(&ap->packet_task, atapi_packet_task, ap); INIT_WORK(&ap->pio_task, ata_pio_task, ap); @@ -4468,6 +4544,11 @@ static int __init ata_init(void) ata_wq = create_workqueue("ata"); if (!ata_wq) return -ENOMEM; + ata_irq_wq = create_workqueue("ata_irq"); + if (!ata_irq_wq) { + destroy_workqueue(ata_wq); + return -ENOMEM; + } printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n"); return 0; @@ -4476,6 +4557,7 @@ static int __init ata_init(void) static void __exit ata_exit(void) { destroy_workqueue(ata_wq); + destroy_workqueue(ata_irq_wq); } module_init(ata_init); @@ -4531,6 +4613,8 @@ EXPORT_SYMBOL_GPL(ata_dev_classify); EXPORT_SYMBOL_GPL(ata_dev_id_string); EXPORT_SYMBOL_GPL(ata_dev_config); EXPORT_SYMBOL_GPL(ata_scsi_simulate); +EXPORT_SYMBOL_GPL(ata_hotplug_unplug); +EXPORT_SYMBOL_GPL(ata_hotplug_plug); #ifdef CONFIG_PCI EXPORT_SYMBOL_GPL(pci_test_config_bits); --- linux-2.6.13-rc3/drivers/scsi/libata-scsi.c.old 2005-07-21 13:35:35.622684850 -0400 +++ linux-2.6.13-rc3/drivers/scsi/libata-scsi.c 2005-07-21 13:42:53.950384627 -0400 @@ -1011,6 +1011,53 @@ static int ata_scsi_qc_complete(struct a return 0; } +static int ata_scsi_qc_abort(struct ata_queued_cmd *qc, u8 drv_stat) +{ + struct scsi_cmnd *cmd = qc->scsicmd; + + cmd->result = SAM_STAT_TASK_ABORTED; //FIXME: Is this what we want? + + qc->scsidone(cmd); + + return 0; +} + +void ata_scsi_prepare_qc_abort(struct ata_queued_cmd *qc) +{ + // For some reason or another, we can't allow a normal scsi_qc_complete + if (qc->complete_fn == ata_scsi_qc_complete); + qc->complete_fn = ata_scsi_qc_abort; +} + +void ata_scsi_handle_plug(struct ata_port *ap) +{ + //Currently SATA only + scsi_add_device(ap->host, 0, 0, 0); +} + +void ata_scsi_handle_unplug(struct ata_port *ap) +{ + //SATA only, no PATA + struct scsi_device *scd = scsi_device_lookup(ap->host, 0, 0, 0); + /* scd might not exist; someone did 'echo "scsi remove-single-device + * ... " > /proc/scsi/scsi' or somebody was turning the key in the + * hotswap bay between on and off really really fast. + */ + if (scd) { + scsi_device_set_state(scd, SDEV_CANCEL); + /* We might have a pending qc on I/O to a removed device, + * however, I argue it's impossible unless we have an 'scd' + * because it means we never completed a 'plug' into the system + * (or no device was present on bootup), so either we have no + * possible I/O, or a qc which 'ata_hotplug_plug_func' took + * care of + */ + ata_check_kill_qc(ap); + scsi_remove_device(scd); + scsi_device_put(scd); + } +} + /** * ata_scsi_translate - Translate then issue SCSI command to ATA device * @ap: ATA port to which the command is addressed --- linux-2.6.13-rc3/drivers/scsi/libata.h.old 2005-07-21 13:35:24.217945955 -0400 +++ linux-2.6.13-rc3/drivers/scsi/libata.h 2005-07-21 13:42:53.955383193 -0400 @@ -40,6 +40,7 @@ extern struct ata_queued_cmd *ata_qc_new extern void ata_qc_free(struct ata_queued_cmd *qc); extern int ata_qc_issue(struct ata_queued_cmd *qc); extern int ata_check_atapi_dma(struct ata_queued_cmd *qc); +extern void ata_check_kill_qc(struct ata_port *ap); extern void ata_dev_select(struct ata_port *ap, unsigned int device, unsigned int wait, unsigned int can_sleep); extern void ata_tf_to_host_nolock(struct ata_port *ap, struct ata_taskfile *tf); @@ -76,6 +77,9 @@ extern void ata_scsi_badcmd(struct scsi_ extern void ata_scsi_rbuf_fill(struct ata_scsi_args *args, unsigned int (*actor) (struct ata_scsi_args *args, u8 *rbuf, unsigned int buflen)); +extern void ata_scsi_prepare_qc_abort(struct ata_queued_cmd *qc); +extern void ata_scsi_handle_plug(struct ata_port *ap); +extern void ata_scsi_handle_unplug(struct ata_port *ap); static inline void ata_bad_scsiop(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) { --- linux-2.6.13-rc3/include/linux/libata.h.old 2005-07-21 13:35:50.548416576 -0400 +++ linux-2.6.13-rc3/include/linux/libata.h 2005-07-21 13:42:53.960381760 -0400 @@ -29,6 +29,7 @@ #include #include #include +#include /* * compile-time options @@ -319,6 +320,9 @@ struct ata_port { struct ata_host_stats stats; struct ata_host_set *host_set; + struct semaphore hotplug_mutex; + struct work_struct hotplug_plug_task; + struct work_struct hotplug_unplug_task; struct work_struct packet_task; struct work_struct pio_task; @@ -326,6 +330,8 @@ struct ata_port { unsigned long pio_task_timeout; void *private_data; + + unsigned int orig_udma_mask; }; struct ata_port_operations { @@ -402,6 +408,8 @@ extern int ata_scsi_queuecmd(struct scsi extern int ata_scsi_error(struct Scsi_Host *host); extern int ata_scsi_release(struct Scsi_Host *host); extern unsigned int ata_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc); +extern void ata_hotplug_unplug(struct ata_port *ap); +extern void ata_hotplug_plug(struct ata_port *ap); /* * Default driver ops implementations */