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s390/pci: Rework __zpci_event_availability() to remove conditional locking

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Clang's compiler based static context analysis does not work with locks
that are conditionally taken like in __zpci_event_availability():

arch/s390/pci/pci_event.c:402:10: warning: mutex 'get_zdev_by_fid(ccdf->fid).state_lock'
  is not held on every path through here [-Wthread-safety-analysis]

Given that code which takes locks conditionally can be considered
suboptimal rework __zpci_event_availability() to get rid of this.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2026-08-05 15:36:26 +02:00 committed by Vasily Gorbik
parent cc459ed00a
commit 9985f26717
1 changed files with 85 additions and 77 deletions
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162
arch/s390/pci/pci_event.c
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@ -387,98 +387,106 @@ static void zpci_event_reappear(struct zpci_dev *zdev)
zpci_dbg(1, "rea fid:%x, fh:%x\n", zdev->fid, zdev->fh);
}
static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
static bool zpci_event_avail_any_device(struct zpci_ccdf_avail *ccdf)
{
struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
bool existing_zdev = !!zdev;
enum zpci_state state;
/* 0x0306 - No handle or fid stored */
if (ccdf->pec != 0x0306)
return false;
/* 0x308 or 0x302 for multiple devices */
zpci_remove_reserved_devices();
zpci_scan_devices();
return true;
}
zpci_dbg(3, "avl fid:%x, fh:%x, pec:%x\n",
ccdf->fid, ccdf->fh, ccdf->pec);
if (existing_zdev)
mutex_lock(&zdev->state_lock);
static void zpci_event_avail_new_device(struct zpci_ccdf_avail *ccdf)
{
struct zpci_dev *zdev;
switch (ccdf->pec) {
case 0x0301: /* Reserved|Standby -> Configured */
if (!zdev) {
zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_CONFIGURED);
if (IS_ERR(zdev))
break;
if (zpci_add_device(zdev)) {
kfree(zdev);
break;
}
} else {
if (zdev->state == ZPCI_FN_STATE_RESERVED)
zpci_event_reappear(zdev);
/* the configuration request may be stale */
else if (zdev->state != ZPCI_FN_STATE_STANDBY)
break;
zdev->state = ZPCI_FN_STATE_CONFIGURED;
zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_CONFIGURED);
if (IS_ERR(zdev))
break;
if (zpci_add_device(zdev)) {
kfree(zdev);
break;
}
zpci_scan_configured_device(zdev, ccdf->fh);
break;
case 0x0302: /* Reserved -> Standby */
if (!zdev) {
zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_STANDBY);
if (IS_ERR(zdev))
break;
if (zpci_add_device(zdev)) {
kfree(zdev);
break;
}
} else {
if (zdev->state == ZPCI_FN_STATE_RESERVED)
zpci_event_reappear(zdev);
zpci_update_fh(zdev, ccdf->fh);
}
break;
case 0x0303: /* Deconfiguration requested */
if (zdev) {
/* The event may have been queued before we configured
* the device.
*/
if (zdev->state != ZPCI_FN_STATE_CONFIGURED)
break;
zpci_update_fh(zdev, ccdf->fh);
zpci_deconfigure_device(zdev);
}
break;
case 0x0304: /* Configured -> Standby|Reserved */
if (zdev) {
/* The event may have been queued before we configured
* the device.:
*/
if (zdev->state == ZPCI_FN_STATE_CONFIGURED)
zpci_event_hard_deconfigured(zdev, ccdf->fh);
/* The 0x0304 event may immediately reserve the device */
if (!clp_get_state(zdev->fid, &state) &&
state == ZPCI_FN_STATE_RESERVED) {
zpci_device_reserved(zdev);
}
}
break;
case 0x0306: /* 0x308 or 0x302 for multiple devices */
zpci_remove_reserved_devices();
zpci_scan_devices();
break;
case 0x0308: /* Standby -> Reserved */
if (!zdev)
zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_STANDBY);
if (IS_ERR(zdev))
break;
zpci_device_reserved(zdev);
break;
default:
if (zpci_add_device(zdev)) {
kfree(zdev);
break;
}
break;
}
if (existing_zdev) {
mutex_unlock(&zdev->state_lock);
zpci_zdev_put(zdev);
}
static void zpci_event_avail_existing_device(struct zpci_dev *zdev, struct zpci_ccdf_avail *ccdf)
{
enum zpci_state state;
switch (ccdf->pec) {
case 0x0301: /* Reserved|Standby -> Configured */
if (zdev->state == ZPCI_FN_STATE_RESERVED)
zpci_event_reappear(zdev);
/* the configuration request may be stale */
else if (zdev->state != ZPCI_FN_STATE_STANDBY)
break;
zdev->state = ZPCI_FN_STATE_CONFIGURED;
zpci_scan_configured_device(zdev, ccdf->fh);
break;
case 0x0302: /* Reserved -> Standby */
if (zdev->state == ZPCI_FN_STATE_RESERVED)
zpci_event_reappear(zdev);
zpci_update_fh(zdev, ccdf->fh);
break;
case 0x0303: /* Deconfiguration requested */
/* The event may have been queued before we configured
* the device.
*/
if (zdev->state != ZPCI_FN_STATE_CONFIGURED)
break;
zpci_update_fh(zdev, ccdf->fh);
zpci_deconfigure_device(zdev);
break;
case 0x0304: /* Configured -> Standby|Reserved */
/* The event may have been queued before we configured
* the device.:
*/
if (zdev->state == ZPCI_FN_STATE_CONFIGURED)
zpci_event_hard_deconfigured(zdev, ccdf->fh);
/* The 0x0304 event may immediately reserve the device */
if (!clp_get_state(zdev->fid, &state) &&
state == ZPCI_FN_STATE_RESERVED) {
zpci_device_reserved(zdev);
}
break;
case 0x0308: /* Standby -> Reserved */
zpci_device_reserved(zdev);
break;
}
}
void zpci_event_availability(void *data)
{
if (zpci_is_enabled())
__zpci_event_availability(data);
struct zpci_ccdf_avail *ccdf = data;
struct zpci_dev *zdev;
if (!zpci_is_enabled())
return;
zpci_dbg(3, "avl fid:%x, fh:%x, pec:%x\n",
ccdf->fid, ccdf->fh, ccdf->pec);
if (zpci_event_avail_any_device(ccdf))
return;
zdev = get_zdev_by_fid(ccdf->fid);
if (!zdev)
return zpci_event_avail_new_device(ccdf);
mutex_lock(&zdev->state_lock);
zpci_event_avail_existing_device(zdev, ccdf);
mutex_unlock(&zdev->state_lock);
zpci_zdev_put(zdev);
}