上次写到系统在运行scsi_error_handle线程之前的初始化过程，系统会在libata-core.c 函数ata_host_register中等待该线程的执行，现在我们从这个线程开始执行：
linux/driver/scsi/scsi_error.c
/**
* scsi_error_handler - SCSI error handler thread
* @data: Host for which we are running.
*
* Notes:
* This is the main error handling loop. This is run as a kernel thread
* for every SCSI host and handles all error handling activity.
**/
int scsi_error_handler(void *data)
{
struct Scsi_Host *shost = data;
/*
* We use TASK_INTERRUPTIBLE so that the thread is not
* counted against the load average as a running process.
* We never actually get interrupted because kthread_run
* disables singal delivery for the created thread.
*/
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
shost->host_failed != shost->host_busy) {
SCSI_LOG_ERROR_RECOVERY(1,
printk("Error handler scsi_eh_%d sleeping\n",
shost->host_no));
schedule();
set_current_state(TASK_INTERRUPTIBLE);
continue;
}
__set_current_state(TASK_RUNNING);
SCSI_LOG_ERROR_RECOVERY(1,
printk("Error handler scsi_eh_%d waking up\n",
shost->host_no));
/*
* We have a host that is failing for some reason. Figure out
* what we need to do to get it up and online again (if we can).
* If we fail, we end up taking the thing offline.
*/
if (shost->transportt->eh_strategy_handler)
shost->transportt->eh_strategy_handler(shost);
else
scsi_unjam_host(shost);
/*
* Note - if the above fails completely, the action is to take
* individual devices offline and flush the queue of any
* outstanding requests that may have been pending. When we
* restart, we restart any I/O to any other devices on the bus
* which are still online.
*/
scsi_restart_operations(shost);
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
SCSI_LOG_ERROR_RECOVERY(1,
printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
shost->ehandler = NULL;
return 0;
}
shost->transportt->eh_strategy_handler(shost); 此处是一个函数指针调用，在之前的文章我已经详细说了这个指针的由来，现在我们看一下这个指针的赋值：
linux/driver/ata/libata-scsi.c
/*
* libata transport template. libata doesn't do real transport stuff.
* It just needs the eh_timed_out hook.
*/
static struct scsi_transport_template ata_scsi_transport_template = {
.eh_strategy_handler = ata_scsi_error,
.eh_timed_out = ata_scsi_timed_out,
.user_scan = ata_scsi_user_scan,
};
该结构在ata_scsi_add_host函数中被传递到上面，上一篇文章对此有提及，可以参考该系列的上一篇文章。
下面我们看一下ata_scsi_error的由来：
linux/driver/ata/libata-eh.c
/**
* ata_scsi_error - SCSI layer error handler callback
* @host: SCSI host on which error occurred
*
* Handles SCSI-layer-thrown error events.
*
* LOCKING:
* Inherited from SCSI layer (none, can sleep)
*
* RETURNS:
* Zero.
*/
void ata_scsi_error(struct Scsi_Host *host)
{
struct ata_port *ap = ata_shost_to_port(host);
int i;
unsigned long flags;
DPRINTK("ENTER\n");
/* synchronize with port task */
ata_port_flush_task(ap);
/* synchronize with host lock and sort out timeouts */
/* For new EH, all qcs are finished in one of three ways -
* normal completion, error completion, and SCSI timeout.
* Both cmpletions can race against SCSI timeout. When normal
* completion wins, the qc never reaches EH. When error
* completion wins, the qc has ATA_QCFLAG_FAILED set.
*
* When SCSI timeout wins, things are a bit more complex.
* Normal or error completion can occur after the timeout but
* before this point. In such cases, both types of
* completions are honored. A scmd is determined to have
* timed out iff its associated qc is active and not failed.
*/
if (ap->ops->error_handler) {
struct scsi_cmnd *scmd, *tmp;
int nr_timedout = 0;
spin_lock_irqsave(ap->lock, flags);
list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
struct ata_queued_cmd *qc;
for (i = 0; i < ATA_MAX_QUEUE; i++) {
qc = __ata_qc_from_tag(ap, i);
if (qc->flags & ATA_QCFLAG_ACTIVE &&
qc->scsicmd == scmd)
break;
}
if (i < ATA_MAX_QUEUE) {
/* the scmd has an associated qc */
if (!(qc->flags & ATA_QCFLAG_FAILED)) {
/* which hasn't failed yet, timeout */
qc->err_mask |= AC_ERR_TIMEOUT;
qc->flags |= ATA_QCFLAG_FAILED;
nr_timedout++;
}
} else {
/* Normal completion occurred after
* SCSI timeout but before this point.
* Successfully complete it.
*/
scmd->retries = scmd->allowed;
scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
}
}
/* If we have timed out qcs. They belong to EH from
* this point but the state of the controller is
* unknown. Freeze the port to make sure the IRQ
* handler doesn't diddle with those qcs. This must
* be done atomically w.r.t. setting QCFLAG_FAILED.
*/
if (nr_timedout)
__ata_port_freeze(ap);
spin_unlock_irqrestore(ap->lock, flags);
/* initialize eh_tries */
ap->eh_tries = ATA_EH_MAX_TRIES;
} else
spin_unlock_wait(ap->lock);
repeat:
/* invoke error handler */
if (ap->ops->error_handler) {
struct ata_link *link;
/* kill fast drain timer */
del_timer_sync(&ap->fastdrain_timer);
/* process port resume request */
ata_eh_handle_port_resume(ap);
/* fetch & clear EH info */
spin_lock_irqsave(ap->lock, flags);
__ata_port_for_each_link(link, ap) {
memset(&link->eh_context, 0, sizeof(link->eh_context));
link->eh_context.i = link->eh_info;
memset(&link->eh_info, 0, sizeof(link->eh_info));
}
ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
ap->pflags &= ~ATA_PFLAG_EH_PENDING;
ap->excl_link = NULL; /* don't maintain exclusion over EH */
spin_unlock_irqrestore(ap->lock, flags);
/* invoke EH, skip if unloading or suspended */
if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
ap->ops->error_handler(ap);
else
ata_eh_finish(ap);
/* process port suspend request */
ata_eh_handle_port_suspend(ap);
/* Exception might have happend after ->error_handler
* recovered the port but before this point. Repeat
* EH in such case.
*/
spin_lock_irqsave(ap->lock, flags);
if (ap->pflags & ATA_PFLAG_EH_PENDING) {
if (--ap->eh_tries) {
spin_unlock_irqrestore(ap->lock, flags);
goto repeat;
}
ata_port_printk(ap, KERN_ERR, "EH pending after %d "
"tries, giving up\n", ATA_EH_MAX_TRIES);
ap->pflags &= ~ATA_PFLAG_EH_PENDING;
}
/* this run is complete, make sure EH info is clear */
__ata_port_for_each_link(link, ap)
memset(&link->eh_info, 0, sizeof(link->eh_info));
/* Clear host_eh_scheduled while holding ap->lock such
* that if exception occurs after this point but
* before EH completion, SCSI midlayer will
* re-initiate EH.
*/
host->host_eh_scheduled = 0;
spin_unlock_irqrestore(ap->lock, flags);
} else {
WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
ap->ops->eng_timeout(ap);
}
/* finish or retry handled scmd's and clean up */
WARN_ON(host->host_failed || !list_empty(&host->eh_cmd_q));
scsi_eh_flush_done_q(&ap->eh_done_q);
/* clean up */
spin_lock_irqsave(ap->lock, flags);
if (ap->pflags & ATA_PFLAG_LOADING)
ap->pflags &= ~ATA_PFLAG_LOADING;
else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0);
if (ap->pflags & ATA_PFLAG_RECOVERED)
ata_port_printk(ap, KERN_INFO, "EH complete\n");
ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);
/* tell wait_eh that we're done */
ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;
wake_up_all(&ap->eh_wait_q);
spin_unlock_irqrestore(ap->lock, flags);
DPRINTK("EXIT\n");
}
注意在这个函数的后面唤醒了之前我们强制等待的初始化主线程，这个函数执行完后这个内核线程执行完了一个周期，等待下一次的唤醒。 我们继续分析这个函数中是如何开始扫描每一个sata口的。
linux/driver/ata/sata_fsl.c
static const struct ata_port_info sata_fsl_port_info[] = {
{
.flags = SATA_FSL_HOST_FLAGS,
.link_flags = SATA_FSL_HOST_LFLAGS,
.pio_mask = 0x1f, /* pio 0-4 */
.udma_mask = 0x7f, /* udma 0-6 */
.port_ops = &sata_fsl_ops,
},
};
static const struct ata_port_operations sata_fsl_ops = {
.check_status = sata_fsl_check_status,
.check_altstatus = sata_fsl_check_status,
.dev_select = ata_noop_dev_select,
.tf_read = sata_fsl_tf_read,
.qc_prep = sata_fsl_qc_prep,
.qc_issue = sata_fsl_qc_issue,
.irq_clear = sata_fsl_irq_clear,
.scr_read = sata_fsl_scr_read,
.scr_write = sata_fsl_scr_write,
.freeze = sata_fsl_freeze,
.thaw = sata_fsl_thaw,
.error_handler = sata_fsl_error_handler,
.post_internal_cmd = sata_fsl_post_internal_cmd,
.port_start = sata_fsl_port_start,
.port_stop = sata_fsl_port_stop,
.pmp_attach = sata_fsl_pmp_attach,
.pmp_detach = sata_fsl_pmp_detach,
};
static void sata_fsl_error_handler(struct ata_port *ap)
{
DPRINTK("in xx_error_handler\n");
/* perform recovery */
sata_pmp_do_eh(ap, ata_std_prereset, sata_fsl_softreset,
sata_std_hardreset, ata_std_postreset,
sata_pmp_std_prereset, sata_fsl_pmp_softreset,
sata_pmp_std_hardreset, sata_pmp_std_postreset);
}
这个函数比较简单，是在在驱动中提供了sata_pmp_do_eh的一个接口， 因为mpc8315 CPU SATA 接口支持PM功能，所以这里使用pmp模块的函数处理。
/linux/driver/libata-pmp.c
/**
* sata_pmp_do_eh - do standard error handling for PMP-enabled host
* @ap: host port to handle error for
* @prereset: prereset method (can be NULL)
* @softreset: softreset method
* @hardreset: hardreset method
* @postreset: postreset method (can be NULL)
* @pmp_prereset: PMP prereset method (can be NULL)
* @pmp_softreset: PMP softreset method (can be NULL)
* @pmp_hardreset: PMP hardreset method (can be NULL)
* @pmp_postreset: PMP postreset method (can be NULL)
*
* Perform standard error handling sequence for PMP-enabled host
* @ap.
*
* LOCKING:
* Kernel thread context (may sleep).
*/
void sata_pmp_do_eh(struct ata_port *ap,
ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
ata_reset_fn_t hardreset, ata_postreset_fn_t postreset,
ata_prereset_fn_t pmp_prereset, ata_reset_fn_t pmp_softreset,
ata_reset_fn_t pmp_hardreset, ata_postreset_fn_t pmp_postreset)
{
DPRINTK("ENTER\n");
ata_eh_autopsy(ap);
ata_eh_report(ap);
sata_pmp_eh_recover(ap, prereset, softreset, hardreset, postreset,
pmp_prereset, pmp_softreset, pmp_hardreset,
pmp_postreset);
ata_eh_finish(ap);
DPRINTK("EXIT\n");
}
到这里往下的部分已经很简单了，读者可以自己查找代码进一步的阅读，我们主要分析函数sata_pmp_eh_recover.
/**
* sata_pmp_eh_recover - recover PMP-enabled port
* @ap: ATA port to recover
* @prereset: prereset method (can be NULL)
* @softreset: softreset method
* @hardreset: hardreset method
* @postreset: postreset method (can be NULL)
* @pmp_prereset: PMP prereset method (can be NULL)
* @pmp_softreset: PMP softreset method (can be NULL)
* @pmp_hardreset: PMP hardreset method (can be NULL)
* @pmp_postreset: PMP postreset method (can be NULL)
*
* Drive EH recovery operation for PMP enabled port @ap. This
* function recovers host and PMP ports with proper retrials and
* fallbacks. Actual recovery operations are performed using
* ata_eh_recover() and sata_pmp_eh_recover_pmp().
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* 0 on success, -errno on failure.
*/
static int sata_pmp_eh_recover(struct ata_port *ap,
ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
ata_reset_fn_t hardreset, ata_postreset_fn_t postreset,
ata_prereset_fn_t pmp_prereset, ata_reset_fn_t pmp_softreset,
ata_reset_fn_t pmp_hardreset, ata_postreset_fn_t pmp_postreset)
{
int pmp_tries, link_tries[SATA_PMP_MAX_PORTS];
struct ata_link *pmp_link = &ap->link;
struct ata_device *pmp_dev = pmp_link->device;
struct ata_eh_context *pmp_ehc = &pmp_link->eh_context;
struct ata_link *link;
struct ata_device *dev;
unsigned int err_mask;
u32 gscr_error, sntf;
int cnt, rc;
pmp_tries = ATA_EH_PMP_TRIES;
ata_port_for_each_link(link, ap)
link_tries[link->pmp] = ATA_EH_PMP_LINK_TRIES;
retry:
/* PMP attached? */
if (!ap->nr_pmp_links) {
rc = ata_eh_recover(ap, prereset, softreset, hardreset,
postreset, NULL);
if (rc) {
ata_link_for_each_dev(dev, &ap->link)
ata_dev_disable(dev);
return rc;
}
if (pmp_dev->class != ATA_DEV_PMP)
return 0;
/* new PMP online */
ata_port_for_each_link(link, ap)
link_tries[link->pmp] = ATA_EH_PMP_LINK_TRIES;
/* fall through */
}
/* recover pmp */
rc = sata_pmp_eh_recover_pmp(ap, prereset, softreset, hardreset,
postreset);
if (rc)
goto pmp_fail;
/* handle disabled links */
rc = sata_pmp_eh_handle_disabled_links(ap);
if (rc)
goto pmp_fail;
/* recover links */
rc = ata_eh_recover(ap, pmp_prereset, pmp_softreset, pmp_hardreset,
pmp_postreset, &link);
if (rc)
goto link_fail;
/* Connection status might have changed while resetting other
* links, check SATA_PMP_GSCR_ERROR before returning.
*/
/* clear SNotification */
rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
if (rc == 0)
sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
/* enable notification */
if (pmp_dev->flags & ATA_DFLAG_AN) {
pmp_dev->gscr[SATA_PMP_GSCR_FEAT_EN] |= SATA_PMP_FEAT_NOTIFY;
err_mask = sata_pmp_write(pmp_dev->link, SATA_PMP_GSCR_FEAT_EN,
pmp_dev->gscr[SATA_PMP_GSCR_FEAT_EN]);
if (err_mask) {
ata_dev_printk(pmp_dev, KERN_ERR, "failed to write "
"PMP_FEAT_EN (Emask=0x%x)\n", err_mask);
rc = -EIO;
goto pmp_fail;
}
}
/* check GSCR_ERROR */
err_mask = sata_pmp_read(pmp_link, SATA_PMP_GSCR_ERROR, &gscr_error);
if (err_mask) {
ata_dev_printk(pmp_dev, KERN_ERR, "failed to read "
"PMP_GSCR_ERROR (Emask=0x%x)\n", err_mask);
rc = -EIO;
goto pmp_fail;
}
cnt = 0;
ata_port_for_each_link(link, ap) {
if (!(gscr_error & (1 << link->pmp)))
continue;
if (sata_pmp_handle_link_fail(link, link_tries)) {
ata_ehi_hotplugged(&link->eh_context.i);
cnt++;
} else {
ata_link_printk(link, KERN_WARNING,
"PHY status changed but maxed out on retries, "
"giving up\n");
ata_link_printk(link, KERN_WARNING,
"Manully issue scan to resume this link\n");
}
}
if (cnt) {
ata_port_printk(ap, KERN_INFO, "PMP SError.N set for some "
"ports, repeating recovery\n");
goto retry;
}
return 0;
link_fail:
if (sata_pmp_handle_link_fail(link, link_tries)) {
pmp_ehc->i.action |= ATA_EH_HARDRESET;
goto retry;
}
/* fall through */
pmp_fail:
/* Control always ends up here after detaching PMP. Shut up
* and return if we're unloading.
*/
if (ap->pflags & ATA_PFLAG_UNLOADING)
return rc;
if (!ap->nr_pmp_links)
goto retry;
if (--pmp_tries) {
ata_port_printk(ap, KERN_WARNING,
"failed to recover PMP, retrying in 5 secs\n");
pmp_ehc->i.action |= ATA_EH_HARDRESET;
ssleep(5);
goto retry;
}
ata_port_printk(ap, KERN_ERR,
"failed to recover PMP after %d tries, giving up\n",
ATA_EH_PMP_TRIES);
sata_pmp_detach(pmp_dev);
ata_dev_disable(pmp_dev);
return rc;
}
/linux/driver/ata/libata_eh.c
/**
* ata_eh_recover - recover host port after error
* @ap: host port to recover
* @prereset: prereset method (can be NULL)
* @softreset: softreset method (can be NULL)
* @hardreset: hardreset method (can be NULL)
* @postreset: postreset method (can be NULL)
* @r_failed_link: out parameter for failed link
*
* This is the alpha and omega, eum and yang, heart and soul of
* libata exception handling. On entry, actions required to
* recover each link and hotplug requests are recorded in the
* link's eh_context. This function executes all the operations
* with appropriate retrials and fallbacks to resurrect failed
* devices, detach goners and greet newcomers.
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
ata_postreset_fn_t postreset,
struct ata_link **r_failed_link)
{
struct ata_link *link;
struct ata_device *dev;
int nr_failed_devs, nr_disabled_devs;
int reset, rc;
unsigned long flags;
DPRINTK("ENTER\n");
/* prep for recovery */
ata_port_for_each_link(link, ap) {
struct ata_eh_context *ehc = &link->eh_context;
/* re-enable link? */
if (ehc->i.action & ATA_EH_ENABLE_LINK) {
ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
spin_lock_irqsave(ap->lock, flags);
link->flags &= ~ATA_LFLAG_DISABLED;
spin_unlock_irqrestore(ap->lock, flags);
ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
}
ata_link_for_each_dev(dev, link) {
if (link->flags & ATA_LFLAG_NO_RETRY)
ehc->tries[dev->devno] = 1;
else
ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
/* collect port action mask recorded in dev actions */
ehc->i.action |= ehc->i.dev_action[dev->devno] &
~ATA_EH_PERDEV_MASK;
ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;
/* process hotplug request */
if (dev->flags & ATA_DFLAG_DETACH)
ata_eh_detach_dev(dev);
if (!ata_dev_enabled(dev) &&
((ehc->i.probe_mask & (1 << dev->devno)) &&
!(ehc->did_probe_mask & (1 << dev->devno)))) {
ata_eh_detach_dev(dev);
ata_dev_init(dev);
ehc->did_probe_mask |= (1 << dev->devno);
ehc->i.action |= ATA_EH_SOFTRESET;
}
}
}
retry:
rc = 0;
nr_failed_devs = 0;
nr_disabled_devs = 0;
reset = 0;
/* if UNLOADING, finish immediately */
if (ap->pflags & ATA_PFLAG_UNLOADING)
goto out;
/* prep for EH */
ata_port_for_each_link(link, ap) {
struct ata_eh_context *ehc = &link->eh_context;
/* skip EH if possible. */
if (ata_eh_skip_recovery(link))
ehc->i.action = 0;
/* do we need to reset? */
if (ehc->i.action & ATA_EH_RESET_MASK)
reset = 1;
ata_link_for_each_dev(dev, link)
ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
}
/* reset */
if (reset) {
/* if PMP is attached, this function only deals with
* downstream links, port should stay thawed.
*/
if (!ap->nr_pmp_links)
ata_eh_freeze_port(ap);
ata_port_for_each_link(link, ap) {
struct ata_eh_context *ehc = &link->eh_context;
if (!(ehc->i.action & ATA_EH_RESET_MASK))
continue;
rc = ata_eh_reset(link, ata_link_nr_vacant(link),
prereset, softreset, hardreset,
postreset);
if (rc) {
ata_link_printk(link, KERN_ERR,
"reset failed, giving up\n");
goto out;
}
}
if (!ap->nr_pmp_links)
ata_eh_thaw_port(ap);
}
/* the rest */
ata_port_for_each_link(link, ap) {
struct ata_eh_context *ehc = &link->eh_context;
/* revalidate existing devices and attach new ones */
rc = ata_eh_revalidate_and_attach(link, &dev);
if (rc)
goto dev_fail;
/* if PMP got attached, return, pmp EH will take care of it */
if (link->device->class == ATA_DEV_PMP) {
ehc->i.action = 0;
return 0;
}
/* configure transfer mode if necessary */
if (ehc->i.flags & ATA_EHI_SETMODE) {
rc = ata_set_mode(link, &dev);
if (rc)
goto dev_fail;
ehc->i.flags &= ~ATA_EHI_SETMODE;
}
if (ehc->i.action & ATA_EHI_LPM)
ata_link_for_each_dev(dev, link)
ata_dev_enable_pm(dev, ap->pm_policy);
/* this link is okay now */
ehc->i.flags = 0;
continue;
dev_fail:
nr_failed_devs++;
if (ata_eh_handle_dev_fail(dev, rc))
nr_disabled_devs++;
if (ap->pflags & ATA_PFLAG_FROZEN) {
/* PMP reset requires working host port.
* Can't retry if it's frozen.
*/
if (ap->nr_pmp_links)
goto out;
break;
}
}
if (nr_failed_devs) {
if (nr_failed_devs != nr_disabled_devs) {
ata_port_printk(ap, KERN_WARNING, "failed to recover "
"some devices, retrying in 5 secs\n");
ssleep(5);
} else {
/* no device left to recover, repeat fast */
msleep(500);
}
goto retry;
}
out:
if (rc && r_failed_link)
*r_failed_link = link;
DPRINTK("EXIT, rc=%d\n", rc);
return rc;
}
int ata_eh_reset(struct ata_link *link, int classify,
ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
{
const int max_tries = ARRAY_SIZE(ata_eh_reset_timeouts);
struct ata_port *ap = link->ap;
struct ata_eh_context *ehc = &link->eh_context;
unsigned int *classes = ehc->classes;
unsigned int lflags = link->flags;
int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
int try = 0;
struct ata_device *dev;
unsigned long deadline, now;
unsigned int tmp_action;
ata_reset_fn_t reset;
unsigned long flags;
u32 sstatus;
int rc;
/* about to reset */
spin_lock_irqsave(ap->lock, flags);
ap->pflags |= ATA_PFLAG_RESETTING;
spin_unlock_irqrestore(ap->lock, flags);
ata_eh_about_to_do(link, NULL, ehc->i.action & ATA_EH_RESET_MASK);
ata_link_for_each_dev(dev, link) {
/* If we issue an SRST then an ATA drive (not ATAPI)
* may change configuration and be in PIO0 timing. If
* we do a hard reset (or are coming from power on)
* this is true for ATA or ATAPI. Until we've set a
* suitable controller mode we should not touch the
* bus as we may be talking too fast.
*/
dev->pio_mode = XFER_PIO_0;
/* If the controller has a pio mode setup function
* then use it to set the chipset to rights. Don't
* touch the DMA setup as that will be dealt with when
* configuring devices.
*/
if (ap->ops->set_piomode)
ap->ops->set_piomode(ap, dev);
}
/* Determine which reset to use and record in ehc->i.action.
* prereset() may examine and modify it.
*/
if (softreset && (!hardreset || (!(lflags & ATA_LFLAG_NO_SRST) &&
!sata_set_spd_needed(link) &&
!(ehc->i.action & ATA_EH_HARDRESET))))
tmp_action = ATA_EH_SOFTRESET;
else
tmp_action = ATA_EH_HARDRESET;
ehc->i.action = (ehc->i.action & ~ATA_EH_RESET_MASK) | tmp_action;
if (prereset) {
rc = prereset(link, jiffies + ATA_EH_PRERESET_TIMEOUT);
if (rc) {
if (rc == -ENOENT) {
ata_link_printk(link, KERN_DEBUG,
"port disabled. ignoring.\n");
ehc->i.action &= ~ATA_EH_RESET_MASK;
ata_link_for_each_dev(dev, link)
classes[dev->devno] = ATA_DEV_NONE;
rc = 0;
} else
ata_link_printk(link, KERN_ERR,
"prereset failed (errno=%d)\n", rc);
goto out;
}
}
/* prereset() might have modified ehc->i.action */
if (ehc->i.action & ATA_EH_HARDRESET)
reset = hardreset;
else if (ehc->i.action & ATA_EH_SOFTRESET)
reset = softreset;
else {
/* prereset told us not to reset, bang classes and return */
ata_link_for_each_dev(dev, link)
classes[dev->devno] = ATA_DEV_NONE;
rc = 0;
goto out;
}
/* did prereset() screw up? if so, fix up to avoid oopsing */
if (!reset) {
if (softreset)
reset = softreset;
else
reset = hardreset;
}
retry:
deadline = jiffies + ata_eh_reset_timeouts[try++];
/* shut up during boot probing */
if (verbose)
ata_link_printk(link, KERN_INFO, "%s resetting link\n",
reset == softreset ? "soft" : "hard");
/* mark that this EH session started with reset */
if (reset == hardreset)
ehc->i.flags |= ATA_EHI_DID_HARDRESET;
else
ehc->i.flags |= ATA_EHI_DID_SOFTRESET;
rc = ata_do_reset(link, reset, classes, deadline);
if (reset == hardreset &&
ata_eh_followup_srst_needed(link, rc, classify, classes)) {
/* okay, let's do follow-up softreset */
reset = softreset;
if (!reset) {
ata_link_printk(link, KERN_ERR,
"follow-up softreset required "
"but no softreset avaliable\n");
rc = -EINVAL;
goto fail;
}
ata_eh_about_to_do(link, NULL, ATA_EH_RESET_MASK);
rc = ata_do_reset(link, reset, classes, deadline);
}
/* -EAGAIN can happen if we skipped followup SRST */
if (rc && rc != -EAGAIN)
goto fail;
/* was classification successful? */
if (classify && classes[0] == ATA_DEV_UNKNOWN &&
!(lflags & ATA_LFLAG_ASSUME_CLASS)) {
if (try < max_tries) {
ata_link_printk(link, KERN_WARNING,
"classification failed\n");
rc = -EINVAL;
goto fail;
}
ata_link_printk(link, KERN_WARNING,
"classfication failed, assuming ATA\n");
lflags |= ATA_LFLAG_ASSUME_ATA;
}
ata_link_for_each_dev(dev, link) {
/* After the reset, the device state is PIO 0 and the
* controller state is undefined. Reset also wakes up
* drives from sleeping mode.
*/
dev->pio_mode = XFER_PIO_0;
dev->flags &= ~ATA_DFLAG_SLEEPING;
if (ata_link_offline(link))
continue;
/* apply class override */
if (lflags & ATA_LFLAG_ASSUME_ATA)
classes[dev->devno] = ATA_DEV_ATA;
else if (lflags & ATA_LFLAG_ASSUME_SEMB)
classes[dev->devno] = ATA_DEV_SEMB_UNSUP; /* not yet */
}
/* record current link speed */
if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
link->sata_spd = (sstatus >> 4) & 0xf;
if (postreset)
postreset(link, classes);
/* reset successful, schedule revalidation */
ata_eh_done(link, NULL, ehc->i.action & ATA_EH_RESET_MASK);
ehc->i.action |= ATA_EH_REVALIDATE;
rc = 0;
out:
/* clear hotplug flag */
ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
spin_lock_irqsave(ap->lock, flags);
ap->pflags &= ~ATA_PFLAG_RESETTING;
spin_unlock_irqrestore(ap->lock, flags);
return rc;
fail:
if (rc == -ERESTART || try >= max_tries)
goto out;
now = jiffies;
if (time_before(now, deadline)) {
unsigned long delta = deadline - now;
ata_link_printk(link, KERN_WARNING, "reset failed "
"(errno=%d), retrying in %u secs\n",
rc, (jiffies_to_msecs(delta) + 999) / 1000);
while (delta)
delta = schedule_timeout_uninterruptible(delta);
}
if (rc == -EPIPE || try == max_tries - 1)
sata_down_spd_limit(link);
if (hardreset)
reset = hardreset;
goto retry;
}
这个函数比较复杂，读者可以自己分析下， 由于篇幅所限就不一一分析下去了。
