Replace three linked lists with xarrays:
- Scsi_Host::__devices collection of scsi_device objects
- Scsi_Host::__targets collection of scsi_target objects
- scsi_target::devices collection of scsi_device objects that
belong to this target
The collection of Scsi_Host objects remains unaltered. It uses the
idr/ida mechanism which already uses xarrays in its implementation.
Add a scsi_target::parent_shost pointer for direct access to a
target's host since the oft called dev_to_shost() needs to loop through
any intermediate (transport supplied) objects between a target and its
parent host. Add a new, trivial access function: starg_to_shost() and
thus allow calls to dev_to_shost(starg->dev.parent) to be replaced
with starg_to_shost(starg). Use this faster replacement in mid-level
source and in an inline function defined in scsi_transport.h .
Against the advice in scsi_devices.h and scsi_host.h this file:
drivers/target/target_core_pscsi.c uses Scsi_Host::__devices directly
and needs a minimal change to allow it to compile and work in the
same fashion.
xarray technical info: all three xarrays are initialized with
XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ flags. When XA_FLAGS_ALLOC is used
a xarray allocates unique index numbers and uses one of the 3 available
marks to manage that allocation. So there are two marks remaining and
they are currently unused. The LOCK_IRQ flags means it calls
spin_lock_irq() internally on xarray modifying operations. xarray
non-modifying operations use the rcu lock.
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
---
drivers/scsi/hosts.c | 8 +++--
drivers/scsi/scsi.c | 43 +++++++++++++++--------
drivers/scsi/scsi_lib.c | 8 ++---
drivers/scsi/scsi_scan.c | 48 +++++++++++++++++--------
drivers/scsi/scsi_sysfs.c | 41 +++++++++++++++-------
drivers/target/target_core_pscsi.c | 2 +-
include/scsi/scsi_device.h | 56 +++++++++++++++++++++++++-----
include/scsi/scsi_host.h | 12 ++++---
include/scsi/scsi_transport.h | 3 +-
9 files changed, 158 insertions(+), 63 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 7ec91c3a66ca..2bba293a497d 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -345,6 +345,8 @@ static void scsi_host_dev_release(struct device *dev)
if (parent)
put_device(parent);
+ xa_destroy(&shost->__targets);
+ xa_destroy(&shost->__devices);
kfree(shost);
}
@@ -382,8 +384,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
shost->host_lock = &shost->default_lock;
spin_lock_init(shost->host_lock);
shost->shost_state = SHOST_CREATED;
- INIT_LIST_HEAD(&shost->__devices);
- INIT_LIST_HEAD(&shost->__targets);
+ xa_init_flags(&shost->__devices, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ);
+ xa_init_flags(&shost->__targets, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ);
INIT_LIST_HEAD(&shost->eh_cmd_q);
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
@@ -502,6 +504,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
fail_index_remove:
ida_simple_remove(&host_index_ida, shost->host_no);
fail_kfree:
+ xa_destroy(&shost->__targets);
+ xa_destroy(&shost->__devices);
kfree(shost);
return NULL;
}
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 56c24a73e0c7..61aa68083f67 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -554,19 +554,32 @@ EXPORT_SYMBOL(scsi_device_put);
struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
struct scsi_device *prev)
{
- struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
- struct scsi_device *next = NULL;
- unsigned long flags;
+ struct scsi_device *next = prev;
+ unsigned long flags, l_idx;
spin_lock_irqsave(shost->host_lock, flags);
- while (list->next != &shost->__devices) {
- next = list_entry(list->next, struct scsi_device, siblings);
- /* skip devices that we can't get a reference to */
- if (!scsi_device_get(next))
- break;
+ if (xa_empty(&shost->__devices)) {
next = NULL;
- list = list->next;
+ goto unlock;
}
+ do {
+ if (!next) { /* get first element iff first iteration */
+ l_idx = 0;
+ next = xa_find(&shost->__devices, &l_idx,
+ scsi_xa_limit_16b.max, XA_PRESENT);
+ } else {
+ l_idx = next->sh_idx,
+ next = xa_find_after(&shost->__devices, &l_idx,
+ scsi_xa_limit_16b.max,
+ XA_PRESENT);
+ }
+ if (next) {
+ /* skip devices that we can't get a reference to */
+ if (!scsi_device_get(next))
+ break;
+ }
+ } while (next);
+unlock:
spin_unlock_irqrestore(shost->host_lock, flags);
if (prev)
@@ -588,7 +601,7 @@ EXPORT_SYMBOL(__scsi_iterate_devices);
void starget_for_each_device(struct scsi_target *starget, void *data,
void (*fn)(struct scsi_device *, void *))
{
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
struct scsi_device *sdev;
shost_for_each_device(sdev, shost) {
@@ -616,7 +629,7 @@ EXPORT_SYMBOL(starget_for_each_device);
void __starget_for_each_device(struct scsi_target *starget, void *data,
void (*fn)(struct scsi_device *, void *))
{
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
struct scsi_device *sdev;
__shost_for_each_device(sdev, shost) {
@@ -645,9 +658,10 @@ EXPORT_SYMBOL(__starget_for_each_device);
struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
u64 lun)
{
+ unsigned long l_idx;
struct scsi_device *sdev;
- list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
+ xa_for_each(&starget->devices, l_idx, sdev) {
if (sdev->sdev_state == SDEV_DEL)
continue;
if (sdev->lun ==lun)
@@ -671,7 +685,7 @@ struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
u64 lun)
{
struct scsi_device *sdev;
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
@@ -703,9 +717,10 @@ EXPORT_SYMBOL(scsi_device_lookup_by_target);
struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
uint channel, uint id, u64 lun)
{
+ unsigned long l_idx;
struct scsi_device *sdev;
- list_for_each_entry(sdev, &shost->__devices, siblings) {
+ xa_for_each(&shost->__devices, l_idx, sdev) {
if (sdev->sdev_state == SDEV_DEL)
continue;
if (sdev->channel == channel && sdev->id == id &&
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 47835c4b4ee0..68df68f54fc8 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -372,9 +372,9 @@ static void scsi_kick_queue(struct request_queue *q)
static void scsi_single_lun_run(struct scsi_device *current_sdev)
{
struct Scsi_Host *shost = current_sdev->host;
- struct scsi_device *sdev, *tmp;
+ struct scsi_device *sdev;
struct scsi_target *starget = scsi_target(current_sdev);
- unsigned long flags;
+ unsigned long flags, l_idx;
spin_lock_irqsave(shost->host_lock, flags);
starget->starget_sdev_user = NULL;
@@ -391,8 +391,8 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev)
spin_lock_irqsave(shost->host_lock, flags);
if (starget->starget_sdev_user)
goto out;
- list_for_each_entry_safe(sdev, tmp, &starget->devices,
- same_target_siblings) {
+ /* XARRAY: was list_for_each_entry_safe(); is this safe ? */
+ xa_for_each(&starget->devices, l_idx, sdev) {
if (sdev == current_sdev)
continue;
if (scsi_device_get(sdev))
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index f2437a7570ce..b8f5850c5a04 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -217,7 +217,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
{
struct scsi_device *sdev;
int display_failure_msg = 1, ret;
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
GFP_KERNEL);
@@ -234,8 +234,9 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
sdev->channel = starget->channel;
mutex_init(&sdev->state_mutex);
sdev->sdev_state = SDEV_CREATED;
- INIT_LIST_HEAD(&sdev->siblings);
- INIT_LIST_HEAD(&sdev->same_target_siblings);
+ /* XARRAY: INIT_LIST_HEAD()s here on list leaves, why ? */
+ sdev->sh_idx = -1;
+ sdev->starg_idx = -1; /* for debugging */
INIT_LIST_HEAD(&sdev->starved_entry);
INIT_LIST_HEAD(&sdev->event_list);
spin_lock_init(&sdev->list_lock);
@@ -306,8 +307,9 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
static void scsi_target_destroy(struct scsi_target *starget)
{
+ struct scsi_target *e_starg;
struct device *dev = &starget->dev;
- struct Scsi_Host *shost = dev_to_shost(dev->parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
unsigned long flags;
BUG_ON(starget->state == STARGET_DEL);
@@ -316,7 +318,10 @@ static void scsi_target_destroy(struct scsi_target *starget)
spin_lock_irqsave(shost->host_lock, flags);
if (shost->hostt->target_destroy)
shost->hostt->target_destroy(starget);
- list_del_init(&starget->siblings);
+ /* XARRAY: was list_del_init(); why the _init ? */
+ e_starg = xa_erase(&shost->__targets, starget->sh_idx);
+ if (e_starg != starget)
+ pr_err("%s: bad xa_erase()\n", __func__);
spin_unlock_irqrestore(shost->host_lock, flags);
put_device(dev);
}
@@ -326,6 +331,7 @@ static void scsi_target_dev_release(struct device *dev)
struct device *parent = dev->parent;
struct scsi_target *starget = to_scsi_target(dev);
+ xa_destroy(&starget->devices);
kfree(starget);
put_device(parent);
}
@@ -344,12 +350,13 @@ EXPORT_SYMBOL(scsi_is_target_device);
static struct scsi_target *__scsi_find_target(struct device *parent,
int channel, uint id)
{
+ unsigned long l_idx;
struct scsi_target *starget, *found_starget = NULL;
struct Scsi_Host *shost = dev_to_shost(parent);
/*
- * Search for an existing target for this sdev.
+ * Search for an existing target for this host.
*/
- list_for_each_entry(starget, &shost->__targets, siblings) {
+ xa_for_each(&shost->__targets, l_idx, starget) {
if (starget->id == id &&
starget->channel == channel) {
found_starget = starget;
@@ -412,6 +419,8 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
struct Scsi_Host *shost = dev_to_shost(parent);
struct device *dev = NULL;
unsigned long flags;
+ unsigned int u_idx;
+ int res;
const int size = sizeof(struct scsi_target)
+ shost->transportt->target_size;
struct scsi_target *starget;
@@ -427,14 +436,15 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
device_initialize(dev);
kref_init(&starget->reap_ref);
dev->parent = get_device(parent);
+ starget->parent_shost = shost;
dev_set_name(dev, "target%d:%d:%d", shost->host_no, channel, id);
dev->bus = &scsi_bus_type;
dev->type = &scsi_target_type;
starget->id = id;
starget->channel = channel;
starget->can_queue = 0;
- INIT_LIST_HEAD(&starget->siblings);
- INIT_LIST_HEAD(&starget->devices);
+ xa_init_flags(&starget->devices, XA_FLAGS_ALLOC | XA_FLAGS_LOCK_IRQ);
+ starget->sh_idx = -1; /* debugging */
starget->state = STARGET_CREATED;
starget->scsi_level = SCSI_2;
starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
@@ -445,7 +455,15 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
if (found_target)
goto found;
- list_add_tail(&starget->siblings, &shost->__targets);
+ /* XARRAY: was list_add_tail(); may get hole in xarray or tail */
+ res = xa_alloc(&shost->__targets, &u_idx, starget, scsi_xa_limit_16b,
+ GFP_ATOMIC);
+ if (res < 0) {
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ pr_err("%s: xa_alloc failure errno=%d\n", __func__, -res);
+ return NULL;
+ }
+ starget->sh_idx = u_idx;
spin_unlock_irqrestore(shost->host_lock, flags);
/* allocate and add */
transport_setup_device(dev);
@@ -1049,7 +1067,7 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
unsigned char *result;
blist_flags_t bflags;
int res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
/*
* The rescan flag is used as an optimization, the first scan of a
@@ -1199,7 +1217,7 @@ static void scsi_sequential_lun_scan(struct scsi_target *starget,
{
uint max_dev_lun;
u64 sparse_lun, lun;
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ struct Scsi_Host *shost = starg_to_shost(starget);
SCSI_LOG_SCAN_BUS(3, starget_printk(KERN_INFO, starget,
"scsi scan: Sequential scan\n"));
@@ -1297,7 +1315,7 @@ static int scsi_report_lun_scan(struct scsi_target *starget, blist_flags_t bflag
struct scsi_lun *lunp, *lun_data;
struct scsi_sense_hdr sshdr;
struct scsi_device *sdev;
- struct Scsi_Host *shost = dev_to_shost(&starget->dev);
+ struct Scsi_Host *shost = starg_to_shost(starget);
int ret = 0;
/*
@@ -1860,11 +1878,11 @@ EXPORT_SYMBOL(scsi_scan_host);
void scsi_forget_host(struct Scsi_Host *shost)
{
struct scsi_device *sdev;
- unsigned long flags;
+ unsigned long flags, l_idx;
restart:
spin_lock_irqsave(shost->host_lock, flags);
- list_for_each_entry(sdev, &shost->__devices, siblings) {
+ xa_for_each(&shost->__devices, l_idx, sdev) {
if (sdev->sdev_state == SDEV_DEL)
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 163dbcb741c1..4bfcf33139a2 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -433,7 +433,7 @@ static void scsi_device_cls_release(struct device *class_dev)
static void scsi_device_dev_release_usercontext(struct work_struct *work)
{
- struct scsi_device *sdev;
+ struct scsi_device *sdev, *e_sdev;
struct device *parent;
struct list_head *this, *tmp;
struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
@@ -447,8 +447,12 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
parent = sdev->sdev_gendev.parent;
spin_lock_irqsave(sdev->host->host_lock, flags);
- list_del(&sdev->siblings);
- list_del(&sdev->same_target_siblings);
+ e_sdev = xa_erase(&sdev->host->__devices, sdev->sh_idx);
+ if (e_sdev != sdev)
+ pr_err("%s: bad xa_erase(host:__devices)\n", __func__);
+ e_sdev = xa_erase(&sdev->sdev_target->devices, sdev->starg_idx);
+ if (e_sdev != sdev)
+ pr_err("%s: bad xa_erase(sdev_target->devices)\n", __func__);
list_del(&sdev->starved_entry);
spin_unlock_irqrestore(sdev->host->host_lock, flags);
@@ -1471,22 +1475,19 @@ EXPORT_SYMBOL(scsi_remove_device);
static void __scsi_remove_target(struct scsi_target *starget)
{
- struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
- unsigned long flags;
+ struct Scsi_Host *shost = starg_to_shost(starget);
struct scsi_device *sdev;
+ unsigned long flags, l_idx;
spin_lock_irqsave(shost->host_lock, flags);
restart:
- list_for_each_entry(sdev, &shost->__devices, siblings) {
+ xa_for_each(&starget->devices, l_idx, sdev) {
/*
* We cannot call scsi_device_get() here, as
* we might've been called from rmmod() causing
* scsi_device_get() to fail the module_is_live()
* check.
*/
- if (sdev->channel != starget->channel ||
- sdev->id != starget->id)
- continue;
if (sdev->sdev_state == SDEV_DEL ||
sdev->sdev_state == SDEV_CANCEL ||
!get_device(&sdev->sdev_gendev))
@@ -1495,6 +1496,7 @@ static void __scsi_remove_target(struct scsi_target *starget)
scsi_remove_device(sdev);
put_device(&sdev->sdev_gendev);
spin_lock_irqsave(shost->host_lock, flags);
+ /* XARRAY: is this goto start of loop correct ? */
goto restart;
}
spin_unlock_irqrestore(shost->host_lock, flags);
@@ -1512,11 +1514,11 @@ void scsi_remove_target(struct device *dev)
{
struct Scsi_Host *shost = dev_to_shost(dev->parent);
struct scsi_target *starget;
- unsigned long flags;
+ unsigned long flags, l_idx;
restart:
spin_lock_irqsave(shost->host_lock, flags);
- list_for_each_entry(starget, &shost->__targets, siblings) {
+ xa_for_each(&shost->__targets, l_idx, starget) {
if (starget->state == STARGET_DEL ||
starget->state == STARGET_REMOVE ||
starget->state == STARGET_CREATED_REMOVE)
@@ -1584,6 +1586,8 @@ static struct device_type scsi_dev_type = {
void scsi_sysfs_device_initialize(struct scsi_device *sdev)
{
+ int res;
+ unsigned int u_idx;
unsigned long flags;
struct Scsi_Host *shost = sdev->host;
struct scsi_target *starget = sdev->sdev_target;
@@ -1614,8 +1618,19 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev)
transport_setup_device(&sdev->sdev_gendev);
spin_lock_irqsave(shost->host_lock, flags);
- list_add_tail(&sdev->same_target_siblings, &starget->devices);
- list_add_tail(&sdev->siblings, &shost->__devices);
+ /* XARRAY: might add in hole */
+ res = xa_alloc(&starget->devices, &u_idx, sdev, scsi_xa_limit_16b,
+ GFP_ATOMIC);
+ if (res < 0)
+ pr_err("%s: xa_alloc 1 failure errno=%d\n", __func__, -res);
+ else
+ sdev->starg_idx = u_idx;
+ res = xa_alloc(&shost->__devices, &u_idx, sdev, scsi_xa_limit_16b,
+ GFP_ATOMIC);
+ if (res < 0)
+ pr_err("%s: xa_alloc 2 failure errno=%d\n", __func__, -res);
+ else
+ sdev->sh_idx = u_idx;
spin_unlock_irqrestore(shost->host_lock, flags);
/*
* device can now only be removed via __scsi_remove_device() so hold
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index c9d92b3e777d..8547fc9ec344 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -496,7 +496,7 @@ static int pscsi_configure_device(struct se_device *dev)
}
spin_lock_irq(sh->host_lock);
- list_for_each_entry(sd, &sh->__devices, siblings) {
+ __shost_for_each_device(sd, sh) {
if ((pdv->pdv_channel_id != sd->channel) ||
(pdv->pdv_target_id != sd->id) ||
(pdv->pdv_lun_id != sd->lun))
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index c3cba2aaf934..dc9de4cc0e79 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -7,7 +7,9 @@
#include <linux/workqueue.h>
#include <linux/blkdev.h>
#include <scsi/scsi.h>
+#include <scsi/scsi_host.h>
#include <linux/atomic.h>
+#include <linux/xarray.h>
struct device;
struct request_queue;
@@ -103,8 +105,8 @@ struct scsi_device {
struct request_queue *request_queue;
/* the next two are protected by the host->host_lock */
- struct list_head siblings; /* list of all devices on this host */
- struct list_head same_target_siblings; /* just the devices sharing same target id */
+ int sh_idx; /* index within host->__devices array */
+ int starg_idx; /* index within sdev_target->devices array */
atomic_t device_busy; /* commands actually active on LLDD */
atomic_t device_blocked; /* Device returned QUEUE_FULL. */
@@ -281,16 +283,18 @@ enum scsi_target_state {
* scsi_target: representation of a scsi target, for now, this is only
* used for single_lun devices. If no one has active IO to the target,
* starget_sdev_user is NULL, else it points to the active sdev.
+ * Invariant: starg->parent_shost == dev_to_shost(starg->dev.parent)
*/
struct scsi_target {
struct scsi_device *starget_sdev_user;
- struct list_head siblings;
- struct list_head devices;
- struct device dev;
+ struct Scsi_Host *parent_shost;
+ int sh_idx; /* index within Scsi_Host::__targets */
struct kref reap_ref; /* last put renders target invisible */
unsigned int channel;
unsigned int id; /* target id ... replace
* scsi_device.id eventually */
+ struct xarray devices; /* scsi_device objects owned by this target */
+ struct device dev;
unsigned int create:1; /* signal that it needs to be added */
unsigned int single_lun:1; /* Indicates we should only
* allow I/O to one of the luns
@@ -329,6 +333,11 @@ static inline struct scsi_target *scsi_target(struct scsi_device *sdev)
#define transport_class_to_starget(class_dev) \
to_scsi_target(class_dev->parent)
+static inline struct Scsi_Host *starg_to_shost(struct scsi_target *starg)
+{
+ return starg->parent_shost;
+}
+
#define starget_printk(prefix, starget, fmt, a...) \
dev_printk(prefix, &(starget)->dev, fmt, ##a)
@@ -365,7 +374,7 @@ extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,
/**
* shost_for_each_device - iterate over all devices of a host
* @sdev: the &struct scsi_device to use as a cursor
- * @shost: the &struct scsi_host to iterate over
+ * @shost: the &struct Scsi_Host to iterate over
*
* Iterator that returns each device attached to @shost. This loop
* takes a reference on each device and releases it at the end. If
@@ -376,21 +385,50 @@ extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,
(sdev); \
(sdev) = __scsi_iterate_devices((shost), (sdev)))
+/* helper for __shost_for_each_device */
+static inline struct scsi_device *__scsi_h2d_1st_it(struct Scsi_Host *shost)
+{
+ unsigned long l_idx = 0;
+
+ return xa_find(&shost->__devices, &l_idx, scsi_xa_limit_16b.max,
+ XA_PRESENT);
+}
+
+/* helper for __shost_for_each_device */
+static inline struct scsi_device *__scsi_h2d_next_it(struct Scsi_Host *shost,
+ struct scsi_device *prev)
+{
+ unsigned long l_idx;
+
+ if (prev) {
+ l_idx = prev->sh_idx,
+ prev = xa_find_after(&shost->__devices, &l_idx,
+ scsi_xa_limit_16b.max, XA_PRESENT);
+ }
+ return prev; /* now either _next_ or NULL */
+}
+
/**
* __shost_for_each_device - iterate over all devices of a host (UNLOCKED)
* @sdev: the &struct scsi_device to use as a cursor
- * @shost: the &struct scsi_host to iterate over
+ * @shost: the &struct Scsi_Host to iterate over
*
* Iterator that returns each device attached to @shost. It does _not_
* take a reference on the scsi_device, so the whole loop must be
- * protected by shost->host_lock.
+ * protected by shost->host_lock (see Note 2).
*
* Note: The only reason to use this is because you need to access the
* device list in interrupt context. Otherwise you really want to use
* shost_for_each_device instead.
+ *
+ * Note 2: The iteration won't fail but dereferencing sdev might. To access
+ * the xarray features (e.g. marks) associated with sdev safely use:
+ * xa_for_each(&shost->__devices, l_idx, next) directly then use l_idx.
*/
#define __shost_for_each_device(sdev, shost) \
- list_for_each_entry((sdev), &((shost)->__devices), siblings)
+ for ((sdev) = __scsi_h2d_1st_it((shost)); \
+ (sdev); \
+ (sdev) = __scsi_h2d_next_it((shost), (sdev)))
extern int scsi_change_queue_depth(struct scsi_device *, int);
extern int scsi_track_queue_full(struct scsi_device *, int);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 822e8cda8d9b..e6386f3d6de1 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -9,6 +9,7 @@
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/blk-mq.h>
+#include <linux/xarray.h>
#include <scsi/scsi.h>
struct block_device;
@@ -29,6 +30,9 @@ struct scsi_transport_template;
#define MODE_INITIATOR 0x01
#define MODE_TARGET 0x02
+/* XARRAY: this limits number of devices (LUs) in host to 64K */
+#define scsi_xa_limit_16b XA_LIMIT(0, USHRT_MAX)
+
struct scsi_host_template {
struct module *module;
const char *name;
@@ -233,7 +237,7 @@ struct scsi_host_template {
* If a host has the ability to discover targets on its own instead
* of scanning the entire bus, it can fill in this function and
* call scsi_scan_host(). This function will be called periodically
- * until it returns 1 with the scsi_host and the elapsed time of
+ * until it returns 1 with the Scsi_Host and the elapsed time of
* the scan in jiffies.
*
* Status: OPTIONAL
@@ -520,9 +524,9 @@ struct Scsi_Host {
* their __ prefixed variants with the lock held. NEVER
* access this list directly from a driver.
*/
- struct list_head __devices;
- struct list_head __targets;
-
+ struct xarray __devices; /* array of scsi_debug objs */
+ struct xarray __targets; /* array of scsi_target objs */
+
struct list_head starved_list;
spinlock_t default_lock;
diff --git a/include/scsi/scsi_transport.h b/include/scsi/scsi_transport.h
index a0458bda3148..3756b264809a 100644
--- a/include/scsi/scsi_transport.h
+++ b/include/scsi/scsi_transport.h
@@ -70,7 +70,8 @@ scsi_transport_reserve_device(struct scsi_transport_template * t, int space)
static inline void *
scsi_transport_target_data(struct scsi_target *starget)
{
- struct Scsi_Host *shost = dev_to_shost(&starget->dev);
+ struct Scsi_Host *shost = starg_to_shost(starget);
+
return (u8 *)starget->starget_data
+ shost->transportt->target_private_offset;
--
2.25.1
