Merge tag 's390-6.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Alexander Gordeev:

 - clear 'Search boot program' flag when 'bootprog' sysfs file is
   written to override a value set from Hardware Management Console

 - fix cyclic dead-lock in zpci_zdev_put() and zpci_scan_devices()
   functions when triggering PCI device recovery using sysfs

 - annotate the expected lock context imbalance in zpci_release_device()
   function to fix a sparse complaint

 - fix the logic to fallback to the return address register value in the
   topmost frame when stack tracing uses a back chain

* tag 's390-6.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/stacktrace: Do not fallback to RA register
  s390/pci: Annotate lock context imbalance in zpci_release_device()
  s390/pci: Fix cyclic dead-lock in zpci_zdev_put() and zpci_scan_devices()
  s390/ipl: Clear SBP flag when bootprog is set

Author: torvalds

.clang-format

@@ -748,6 +748,7 @@ ForEachMacros:
   - 'ynl_attr_for_each_nested'
   - 'ynl_attr_for_each_payload'
   - 'zorro_for_each_dev'
+  - 'zpci_bus_for_each'
 
 IncludeBlocks: Preserve
 IncludeCategories:

arch/s390/include/uapi/asm/ipl.h

@@ -15,6 +15,7 @@ struct ipl_pl_hdr {
 #define IPL_PL_FLAG_IPLPS	0x80
 #define IPL_PL_FLAG_SIPL	0x40
 #define IPL_PL_FLAG_IPLSR	0x20
+#define IPL_PL_FLAG_SBP		0x10
 
 /* IPL Parameter Block header */
 struct ipl_pb_hdr {

arch/s390/kernel/ipl.c

@@ -262,6 +262,24 @@ static struct kobj_attribute sys_##_prefix##_##_name##_attr =		\
 			sys_##_prefix##_##_name##_show,			\
 			sys_##_prefix##_##_name##_store)
 
+#define DEFINE_IPL_ATTR_BOOTPROG_RW(_prefix, _name, _fmt_out, _fmt_in, _hdr, _value)	\
+	IPL_ATTR_SHOW_FN(_prefix, _name, _fmt_out, (unsigned long long) _value)		\
+static ssize_t sys_##_prefix##_##_name##_store(struct kobject *kobj,			\
+		struct kobj_attribute *attr,						\
+		const char *buf, size_t len)						\
+{											\
+	unsigned long long value;							\
+	if (sscanf(buf, _fmt_in, &value) != 1)						\
+		return -EINVAL;								\
+	(_value) = value;								\
+	(_hdr).flags &= ~IPL_PL_FLAG_SBP;						\
+	return len;									\
+}											\
+static struct kobj_attribute sys_##_prefix##_##_name##_attr =				\
+	__ATTR(_name, 0644,								\
+			sys_##_prefix##_##_name##_show,					\
+			sys_##_prefix##_##_name##_store)
+
 #define DEFINE_IPL_ATTR_STR_RW(_prefix, _name, _fmt_out, _fmt_in, _value)\
 IPL_ATTR_SHOW_FN(_prefix, _name, _fmt_out, _value)			\
 static ssize_t sys_##_prefix##_##_name##_store(struct kobject *kobj,	\
@@ -818,12 +836,13 @@ DEFINE_IPL_ATTR_RW(reipl_fcp, wwpn, "0x%016llx\n", "%llx\n",
 		   reipl_block_fcp->fcp.wwpn);
 DEFINE_IPL_ATTR_RW(reipl_fcp, lun, "0x%016llx\n", "%llx\n",
 		   reipl_block_fcp->fcp.lun);
-DEFINE_IPL_ATTR_RW(reipl_fcp, bootprog, "%lld\n", "%lld\n",
-		   reipl_block_fcp->fcp.bootprog);
 DEFINE_IPL_ATTR_RW(reipl_fcp, br_lba, "%lld\n", "%lld\n",
 		   reipl_block_fcp->fcp.br_lba);
 DEFINE_IPL_ATTR_RW(reipl_fcp, device, "0.0.%04llx\n", "0.0.%llx\n",
 		   reipl_block_fcp->fcp.devno);
+DEFINE_IPL_ATTR_BOOTPROG_RW(reipl_fcp, bootprog, "%lld\n", "%lld\n",
+			    reipl_block_fcp->hdr,
+			    reipl_block_fcp->fcp.bootprog);
 
 static void reipl_get_ascii_loadparm(char *loadparm,
 				     struct ipl_parameter_block *ibp)
@@ -942,10 +961,11 @@ DEFINE_IPL_ATTR_RW(reipl_nvme, fid, "0x%08llx\n", "%llx\n",
 		   reipl_block_nvme->nvme.fid);
 DEFINE_IPL_ATTR_RW(reipl_nvme, nsid, "0x%08llx\n", "%llx\n",
 		   reipl_block_nvme->nvme.nsid);
-DEFINE_IPL_ATTR_RW(reipl_nvme, bootprog, "%lld\n", "%lld\n",
-		   reipl_block_nvme->nvme.bootprog);
 DEFINE_IPL_ATTR_RW(reipl_nvme, br_lba, "%lld\n", "%lld\n",
 		   reipl_block_nvme->nvme.br_lba);
+DEFINE_IPL_ATTR_BOOTPROG_RW(reipl_nvme, bootprog, "%lld\n", "%lld\n",
+			    reipl_block_nvme->hdr,
+			    reipl_block_nvme->nvme.bootprog);
 
 static struct attribute *reipl_nvme_attrs[] = {
 	&sys_reipl_nvme_fid_attr.attr,
@@ -1038,8 +1058,9 @@ static const struct bin_attribute *const reipl_eckd_bin_attrs[] = {
 };
 
 DEFINE_IPL_CCW_ATTR_RW(reipl_eckd, device, reipl_block_eckd->eckd);
-DEFINE_IPL_ATTR_RW(reipl_eckd, bootprog, "%lld\n", "%lld\n",
-		   reipl_block_eckd->eckd.bootprog);
+DEFINE_IPL_ATTR_BOOTPROG_RW(reipl_eckd, bootprog, "%lld\n", "%lld\n",
+			    reipl_block_eckd->hdr,
+			    reipl_block_eckd->eckd.bootprog);
 
 static struct attribute *reipl_eckd_attrs[] = {
 	&sys_reipl_eckd_device_attr.attr,
@@ -1567,12 +1588,13 @@ DEFINE_IPL_ATTR_RW(dump_fcp, wwpn, "0x%016llx\n", "%llx\n",
 		   dump_block_fcp->fcp.wwpn);
 DEFINE_IPL_ATTR_RW(dump_fcp, lun, "0x%016llx\n", "%llx\n",
 		   dump_block_fcp->fcp.lun);
-DEFINE_IPL_ATTR_RW(dump_fcp, bootprog, "%lld\n", "%lld\n",
-		   dump_block_fcp->fcp.bootprog);
 DEFINE_IPL_ATTR_RW(dump_fcp, br_lba, "%lld\n", "%lld\n",
 		   dump_block_fcp->fcp.br_lba);
 DEFINE_IPL_ATTR_RW(dump_fcp, device, "0.0.%04llx\n", "0.0.%llx\n",
 		   dump_block_fcp->fcp.devno);
+DEFINE_IPL_ATTR_BOOTPROG_RW(dump_fcp, bootprog, "%lld\n", "%lld\n",
+			    dump_block_fcp->hdr,
+			    dump_block_fcp->fcp.bootprog);
 
 DEFINE_IPL_ATTR_SCP_DATA_RW(dump_fcp, dump_block_fcp->hdr,
 			    dump_block_fcp->fcp,
@@ -1604,10 +1626,11 @@ DEFINE_IPL_ATTR_RW(dump_nvme, fid, "0x%08llx\n", "%llx\n",
 		   dump_block_nvme->nvme.fid);
 DEFINE_IPL_ATTR_RW(dump_nvme, nsid, "0x%08llx\n", "%llx\n",
 		   dump_block_nvme->nvme.nsid);
-DEFINE_IPL_ATTR_RW(dump_nvme, bootprog, "%lld\n", "%llx\n",
-		   dump_block_nvme->nvme.bootprog);
 DEFINE_IPL_ATTR_RW(dump_nvme, br_lba, "%lld\n", "%llx\n",
 		   dump_block_nvme->nvme.br_lba);
+DEFINE_IPL_ATTR_BOOTPROG_RW(dump_nvme, bootprog, "%lld\n", "%llx\n",
+			    dump_block_nvme->hdr,
+			    dump_block_nvme->nvme.bootprog);
 
 DEFINE_IPL_ATTR_SCP_DATA_RW(dump_nvme, dump_block_nvme->hdr,
 			    dump_block_nvme->nvme,
@@ -1635,8 +1658,9 @@ static const struct attribute_group dump_nvme_attr_group = {
 
 /* ECKD dump device attributes */
 DEFINE_IPL_CCW_ATTR_RW(dump_eckd, device, dump_block_eckd->eckd);
-DEFINE_IPL_ATTR_RW(dump_eckd, bootprog, "%lld\n", "%llx\n",
-		   dump_block_eckd->eckd.bootprog);
+DEFINE_IPL_ATTR_BOOTPROG_RW(dump_eckd, bootprog, "%lld\n", "%llx\n",
+			    dump_block_eckd->hdr,
+			    dump_block_eckd->eckd.bootprog);
 
 IPL_ATTR_BR_CHR_SHOW_FN(dump, dump_block_eckd->eckd);
 IPL_ATTR_BR_CHR_STORE_FN(dump, dump_block_eckd->eckd);

arch/s390/kernel/stacktrace.c

@@ -104,7 +104,6 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
 	struct stack_frame_vdso_wrapper __user *sf_vdso;
 	struct stack_frame_user __user *sf;
 	unsigned long ip, sp;
-	bool first = true;
 
 	if (!current->mm)
 		return;
@@ -133,24 +132,11 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
 			if (__get_user(ip, &sf->gprs[8]))
 				break;
 		}
-		/* Sanity check: ABI requires SP to be 8 byte aligned. */
-		if (sp & 0x7)
+		/* Validate SP and RA (ABI requires SP to be 8 byte aligned). */
+		if (sp & 0x7 || ip_invalid(ip))
 			break;
-		if (ip_invalid(ip)) {
-			/*
-			 * If the instruction address is invalid, and this
-			 * is the first stack frame, assume r14 has not
-			 * been written to the stack yet. Otherwise exit.
-			 */
-			if (!first)
-				break;
-			ip = regs->gprs[14];
-			if (ip_invalid(ip))
-				break;
-		}
 		if (!store_ip(consume_entry, cookie, entry, perf, ip))
 			break;
-		first = false;
 	}
 	pagefault_enable();
 }

arch/s390/pci/pci.c

@@ -961,6 +961,7 @@ void zpci_device_reserved(struct zpci_dev *zdev)
 }
 
 void zpci_release_device(struct kref *kref)
+	__releases(&zpci_list_lock)
 {
 	struct zpci_dev *zdev = container_of(kref, struct zpci_dev, kref);
 
@@ -1148,6 +1149,7 @@ static void zpci_add_devices(struct list_head *scan_list)
 
 int zpci_scan_devices(void)
 {
+	struct zpci_bus *zbus;
 	LIST_HEAD(scan_list);
 	int rc;
 
@@ -1156,7 +1158,10 @@ int zpci_scan_devices(void)
 		return rc;
 
 	zpci_add_devices(&scan_list);
-	zpci_bus_scan_busses();
+	zpci_bus_for_each(zbus) {
+		zpci_bus_scan_bus(zbus);
+		cond_resched();
+	}
 	return 0;
 }
 

arch/s390/pci/pci_bus.c

@@ -153,23 +153,6 @@ int zpci_bus_scan_bus(struct zpci_bus *zbus)
 	return ret;
 }
 
-/* zpci_bus_scan_busses - Scan all registered busses
- *
- * Scan all available zbusses
- *
- */
-void zpci_bus_scan_busses(void)
-{
-	struct zpci_bus *zbus = NULL;
-
-	mutex_lock(&zbus_list_lock);
-	list_for_each_entry(zbus, &zbus_list, bus_next) {
-		zpci_bus_scan_bus(zbus);
-		cond_resched();
-	}
-	mutex_unlock(&zbus_list_lock);
-}
-
 static bool zpci_bus_is_multifunction_root(struct zpci_dev *zdev)
 {
 	return !s390_pci_no_rid && zdev->rid_available &&
@@ -222,10 +205,29 @@ static int zpci_bus_create_pci_bus(struct zpci_bus *zbus, struct zpci_dev *fr, s
 	return -ENOMEM;
 }
 
-static void zpci_bus_release(struct kref *kref)
+/**
+ * zpci_bus_release - Un-initialize resources associated with the zbus and
+ *		      free memory
+ * @kref:	refcount * that is part of struct zpci_bus
+ *
+ * MUST be called with `zbus_list_lock` held, but the lock is released during
+ * run of the function.
+ */
+static inline void zpci_bus_release(struct kref *kref)
+	__releases(&zbus_list_lock)
 {
 	struct zpci_bus *zbus = container_of(kref, struct zpci_bus, kref);
 
+	lockdep_assert_held(&zbus_list_lock);
+
+	list_del(&zbus->bus_next);
+	mutex_unlock(&zbus_list_lock);
+
+	/*
+	 * At this point no-one should see this object, or be able to get a new
+	 * reference to it.
+	 */
+
 	if (zbus->bus) {
 		pci_lock_rescan_remove();
 		pci_stop_root_bus(zbus->bus);
@@ -237,16 +239,19 @@ static void zpci_bus_release(struct kref *kref)
 		pci_unlock_rescan_remove();
 	}
 
-	mutex_lock(&zbus_list_lock);
-	list_del(&zbus->bus_next);
-	mutex_unlock(&zbus_list_lock);
 	zpci_remove_parent_msi_domain(zbus);
 	kfree(zbus);
 }
 
-static void zpci_bus_put(struct zpci_bus *zbus)
+static inline void __zpci_bus_get(struct zpci_bus *zbus)
+{
+	lockdep_assert_held(&zbus_list_lock);
+	kref_get(&zbus->kref);
+}
+
+static inline void zpci_bus_put(struct zpci_bus *zbus)
 {
-	kref_put(&zbus->kref, zpci_bus_release);
+	kref_put_mutex(&zbus->kref, zpci_bus_release, &zbus_list_lock);
 }
 
 static struct zpci_bus *zpci_bus_get(int topo, bool topo_is_tid)
@@ -258,7 +263,7 @@ static struct zpci_bus *zpci_bus_get(int topo, bool topo_is_tid)
 		if (!zbus->multifunction)
 			continue;
 		if (topo_is_tid == zbus->topo_is_tid && topo == zbus->topo) {
-			kref_get(&zbus->kref);
+			__zpci_bus_get(zbus);
 			goto out_unlock;
 		}
 	}
@@ -268,6 +273,44 @@ static struct zpci_bus *zpci_bus_get(int topo, bool topo_is_tid)
 	return zbus;
 }
 
+/**
+ * zpci_bus_get_next - get the next zbus object from given position in the list
+ * @pos:	current position/cursor in the global zbus list
+ *
+ * Acquires and releases references as the cursor iterates (might also free/
+ * release the cursor). Is tolerant of concurrent operations on the list.
+ *
+ * To begin the iteration, set *@pos to %NULL before calling the function.
+ *
+ * *@pos is set to %NULL in cases where either the list is empty, or *@pos is
+ * the last element in the list.
+ *
+ * Context: Process context. May sleep.
+ */
+void zpci_bus_get_next(struct zpci_bus **pos)
+{
+	struct zpci_bus *curp = *pos, *next = NULL;
+
+	mutex_lock(&zbus_list_lock);
+	if (curp)
+		next = list_next_entry(curp, bus_next);
+	else
+		next = list_first_entry(&zbus_list, typeof(*curp), bus_next);
+
+	if (list_entry_is_head(next, &zbus_list, bus_next))
+		next = NULL;
+
+	if (next)
+		__zpci_bus_get(next);
+
+	*pos = next;
+	mutex_unlock(&zbus_list_lock);
+
+	/* zpci_bus_put() might drop refcount to 0 and locks zbus_list_lock */
+	if (curp)
+		zpci_bus_put(curp);
+}
+
 static struct zpci_bus *zpci_bus_alloc(int topo, bool topo_is_tid)
 {
 	struct zpci_bus *zbus;
@@ -279,9 +322,6 @@ static struct zpci_bus *zpci_bus_alloc(int topo, bool topo_is_tid)
 	zbus->topo = topo;
 	zbus->topo_is_tid = topo_is_tid;
 	INIT_LIST_HEAD(&zbus->bus_next);
-	mutex_lock(&zbus_list_lock);
-	list_add_tail(&zbus->bus_next, &zbus_list);
-	mutex_unlock(&zbus_list_lock);
 
 	kref_init(&zbus->kref);
 	INIT_LIST_HEAD(&zbus->resources);
@@ -291,6 +331,10 @@ static struct zpci_bus *zpci_bus_alloc(int topo, bool topo_is_tid)
 	zbus->bus_resource.flags = IORESOURCE_BUS;
 	pci_add_resource(&zbus->resources, &zbus->bus_resource);
 
+	mutex_lock(&zbus_list_lock);
+	list_add_tail(&zbus->bus_next, &zbus_list);
+	mutex_unlock(&zbus_list_lock);
+
 	return zbus;
 }
 

arch/s390/pci/pci_bus.h

@@ -15,7 +15,20 @@ int zpci_bus_device_register(struct zpci_dev *zdev, struct pci_ops *ops);
 void zpci_bus_device_unregister(struct zpci_dev *zdev);
 
 int zpci_bus_scan_bus(struct zpci_bus *zbus);
-void zpci_bus_scan_busses(void);
+void zpci_bus_get_next(struct zpci_bus **pos);
+
+/**
+ * zpci_bus_for_each - iterate over all the registered zbus objects
+ * @pos:	a struct zpci_bus * as cursor
+ *
+ * Acquires and releases references as the cursor iterates over the registered
+ * objects. Is tolerant against concurrent removals of objects.
+ *
+ * Context: Process context. May sleep.
+ */
+#define zpci_bus_for_each(pos)					     \
+	for ((pos) = NULL, zpci_bus_get_next(&(pos)); (pos) != NULL; \
+	     zpci_bus_get_next(&(pos)))
 
 int zpci_bus_scan_device(struct zpci_dev *zdev);
 void zpci_bus_remove_device(struct zpci_dev *zdev, bool set_error);