Merge branches 'doc.2023.01.05a', 'fixes.2023.01.23a', 'kvfree.2023.0…

…1.03a', 'srcu.2023.01.03a', 'srcu-always.2023.02.02a', 'tasks.2023.01.03a', 'torture.2023.01.05a' and 'torturescript.2023.01.03a' into HEAD doc.2023.01.05a: Documentation update. fixes.2023.01.23a: Miscellaneous fixes. kvfree.2023.01.03a: kvfree_rcu() updates. srcu.2023.01.03a: SRCU updates. srcu-always.2023.02.02a: Finish making SRCU be unconditionally available. tasks.2023.01.03a: Tasks-RCU updates. torture.2023.01.05a: Torture-test updates. torturescript.2023.01.03a: Torture-test scripting updates.
mariux64 · Feb 3, 2023 · 8e1704b · 8e1704b
8 parents 5e013dc + cf7066b + 608723c + dafc4d1 + 5634469 + a4fcfbe + d52d3a2 + 5a6cd56
commit 8e1704b
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Showing 39 changed files with 1,010 additions and 506 deletions.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
@@ -5113,6 +5113,11 @@
 			rcupdate.rcu_cpu_stall_timeout to be used (after
 			conversion from seconds to milliseconds).
 
+	rcupdate.rcu_exp_stall_task_details= [KNL]
+			Print stack dumps of any tasks blocking the
+			current expedited RCU grace period during an
+			expedited RCU CPU stall warning.
+
 	rcupdate.rcu_expedited= [KNL]
 			Use expedited grace-period primitives, for
 			example, synchronize_rcu_expedited() instead

diff --git a/drivers/base/core.c b/drivers/base/core.c
@@ -181,7 +181,6 @@ void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode)
 }
 EXPORT_SYMBOL_GPL(fw_devlink_purge_absent_suppliers);
 
-#ifdef CONFIG_SRCU
 static DEFINE_MUTEX(device_links_lock);
 DEFINE_STATIC_SRCU(device_links_srcu);
 
@@ -220,47 +219,6 @@ static void device_link_remove_from_lists(struct device_link *link)
 	list_del_rcu(&link->s_node);
 	list_del_rcu(&link->c_node);
 }
-#else /* !CONFIG_SRCU */
-static DECLARE_RWSEM(device_links_lock);
-
-static inline void device_links_write_lock(void)
-{
-	down_write(&device_links_lock);
-}
-
-static inline void device_links_write_unlock(void)
-{
-	up_write(&device_links_lock);
-}
-
-int device_links_read_lock(void)
-{
-	down_read(&device_links_lock);
-	return 0;
-}
-
-void device_links_read_unlock(int not_used)
-{
-	up_read(&device_links_lock);
-}
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-int device_links_read_lock_held(void)
-{
-	return lockdep_is_held(&device_links_lock);
-}
-#endif
-
-static inline void device_link_synchronize_removal(void)
-{
-}
-
-static void device_link_remove_from_lists(struct device_link *link)
-{
-	list_del(&link->s_node);
-	list_del(&link->c_node);
-}
-#endif /* !CONFIG_SRCU */
 
 static bool device_is_ancestor(struct device *dev, struct device *target)
 {

diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 menuconfig DAX
 	tristate "DAX: direct access to differentiated memory"
-	select SRCU
 	default m if NVDIMM_DAX
 
 if DAX

diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig
@@ -2,7 +2,6 @@
 config STM
 	tristate "System Trace Module devices"
 	select CONFIGFS_FS
-	select SRCU
 	help
 	  A System Trace Module (STM) is a device exporting data in System
 	  Trace Protocol (STP) format as defined by MIPI STP standards.

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
@@ -6,7 +6,6 @@
 menuconfig MD
 	bool "Multiple devices driver support (RAID and LVM)"
 	depends on BLOCK
-	select SRCU
 	help
 	  Support multiple physical spindles through a single logical device.
 	  Required for RAID and logical volume management.

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
@@ -334,7 +334,6 @@ config NETCONSOLE_DYNAMIC
 
 config NETPOLL
 	def_bool NETCONSOLE
-	select SRCU
 
 config NET_POLL_CONTROLLER
 	def_bool NETPOLL

diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
@@ -258,7 +258,7 @@ config PCIE_MEDIATEK_GEN3
 	  MediaTek SoCs.
 
 config VMD
-	depends on PCI_MSI && X86_64 && SRCU && !UML
+	depends on PCI_MSI && X86_64 && !UML
 	tristate "Intel Volume Management Device Driver"
 	help
 	  Adds support for the Intel Volume Management Device (VMD). VMD is a

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
@@ -17,7 +17,6 @@ config BTRFS_FS
 	select FS_IOMAP
 	select RAID6_PQ
 	select XOR_BLOCKS
-	select SRCU
 	depends on PAGE_SIZE_LESS_THAN_256KB
 
 	help

diff --git a/fs/locks.c b/fs/locks.c
@@ -1889,7 +1889,6 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
 }
 EXPORT_SYMBOL(generic_setlease);
 
-#if IS_ENABLED(CONFIG_SRCU)
 /*
  * Kernel subsystems can register to be notified on any attempt to set
  * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
@@ -1923,30 +1922,6 @@ void lease_unregister_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL_GPL(lease_unregister_notifier);
 
-#else /* !IS_ENABLED(CONFIG_SRCU) */
-static inline void
-lease_notifier_chain_init(void)
-{
-}
-
-static inline void
-setlease_notifier(long arg, struct file_lock *lease)
-{
-}
-
-int lease_register_notifier(struct notifier_block *nb)
-{
-	return 0;
-}
-EXPORT_SYMBOL_GPL(lease_register_notifier);
-
-void lease_unregister_notifier(struct notifier_block *nb)
-{
-}
-EXPORT_SYMBOL_GPL(lease_unregister_notifier);
-
-#endif /* IS_ENABLED(CONFIG_SRCU) */
-
 /**
  * vfs_setlease        -       sets a lease on an open file
  * @filp:	file pointer

diff --git a/fs/notify/Kconfig b/fs/notify/Kconfig
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config FSNOTIFY
 	def_bool n
-	select SRCU
 
 source "fs/notify/dnotify/Kconfig"
 source "fs/notify/inotify/Kconfig"

diff --git a/fs/quota/Kconfig b/fs/quota/Kconfig
@@ -6,7 +6,6 @@
 config QUOTA
 	bool "Quota support"
 	select QUOTACTL
-	select SRCU
 	help
 	  If you say Y here, you will be able to set per user limits for disk
 	  usage (also called disk quotas). Currently, it works for the

diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
@@ -139,7 +139,7 @@ static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
 	if (last) {
 		n->next = last->next;
 		n->pprev = &last->next;
-		rcu_assign_pointer(hlist_next_rcu(last), n);
+		rcu_assign_pointer(hlist_nulls_next_rcu(last), n);
 	} else {
 		hlist_nulls_add_head_rcu(n, h);
 	}

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
@@ -238,6 +238,7 @@ void synchronize_rcu_tasks_rude(void);
 
 #define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t, false)
 void exit_tasks_rcu_start(void);
+void exit_tasks_rcu_stop(void);
 void exit_tasks_rcu_finish(void);
 #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
 #define rcu_tasks_classic_qs(t, preempt) do { } while (0)
@@ -246,6 +247,7 @@ void exit_tasks_rcu_finish(void);
 #define call_rcu_tasks call_rcu
 #define synchronize_rcu_tasks synchronize_rcu
 static inline void exit_tasks_rcu_start(void) { }
+static inline void exit_tasks_rcu_stop(void) { }
 static inline void exit_tasks_rcu_finish(void) { }
 #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
 
@@ -374,11 +376,18 @@ static inline int debug_lockdep_rcu_enabled(void)
  * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met
  * @c: condition to check
  * @s: informative message
+ *
+ * This checks debug_lockdep_rcu_enabled() before checking (c) to
+ * prevent early boot splats due to lockdep not yet being initialized,
+ * and rechecks it after checking (c) to prevent false-positive splats
+ * due to races with lockdep being disabled.  See commit 3066820034b5dd
+ * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail.
  */
 #define RCU_LOCKDEP_WARN(c, s)						\
 	do {								\
 		static bool __section(".data.unlikely") __warned;	\
-		if ((c) && debug_lockdep_rcu_enabled() && !__warned) {	\
+		if (debug_lockdep_rcu_enabled() && (c) &&		\
+		    debug_lockdep_rcu_enabled() && !__warned) {		\
 			__warned = true;				\
 			lockdep_rcu_suspicious(__FILE__, __LINE__, s);	\
 		}							\
@@ -1004,15 +1013,17 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 #define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,		\
 	kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__)
 
+#define kvfree_rcu_mightsleep(ptr) kvfree_rcu_arg_1(ptr)
+#define kfree_rcu_mightsleep(ptr) kvfree_rcu_mightsleep(ptr)
+
 #define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME
 #define kvfree_rcu_arg_2(ptr, rhf)					\
 do {									\
 	typeof (ptr) ___p = (ptr);					\
 									\
 	if (___p) {									\
 		BUILD_BUG_ON(!__is_kvfree_rcu_offset(offsetof(typeof(*(ptr)), rhf)));	\
-		kvfree_call_rcu(&((___p)->rhf), (rcu_callback_t)(unsigned long)		\
-			(offsetof(typeof(*(ptr)), rhf)));				\
+		kvfree_call_rcu(&((___p)->rhf), (void *) (___p));			\
 	}										\
 } while (0)
 
@@ -1021,7 +1032,7 @@ do {								\
 	typeof(ptr) ___p = (ptr);				\
 								\
 	if (___p)						\
-		kvfree_call_rcu(NULL, (rcu_callback_t) (___p));	\
+		kvfree_call_rcu(NULL, (void *) (___p));		\
 } while (0)
 
 /*

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
@@ -98,25 +98,25 @@ static inline void synchronize_rcu_expedited(void)
  */
 extern void kvfree(const void *addr);
 
-static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr)
 {
 	if (head) {
-		call_rcu(head, func);
+		call_rcu(head, (rcu_callback_t) ((void *) head - ptr));
 		return;
 	}
 
 	// kvfree_rcu(one_arg) call.
 	might_sleep();
 	synchronize_rcu();
-	kvfree((void *) func);
+	kvfree(ptr);
 }
 
 #ifdef CONFIG_KASAN_GENERIC
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
 #else
-static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
+static inline void kvfree_call_rcu(struct rcu_head *head, void *ptr)
 {
-	__kvfree_call_rcu(head, func);
+	__kvfree_call_rcu(head, ptr);
 }
 #endif
 

diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
@@ -33,7 +33,7 @@ static inline void rcu_virt_note_context_switch(void)
 }
 
 void synchronize_rcu_expedited(void);
-void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
+void kvfree_call_rcu(struct rcu_head *head, void *ptr);
 
 void rcu_barrier(void);
 bool rcu_eqs_special_set(int cpu);

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
@@ -214,6 +214,34 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
 	return retval;
 }
 
+/**
+ * srcu_down_read - register a new reader for an SRCU-protected structure.
+ * @ssp: srcu_struct in which to register the new reader.
+ *
+ * Enter a semaphore-like SRCU read-side critical section.  Note that
+ * SRCU read-side critical sections may be nested.  However, it is
+ * illegal to call anything that waits on an SRCU grace period for the
+ * same srcu_struct, whether directly or indirectly.  Please note that
+ * one way to indirectly wait on an SRCU grace period is to acquire
+ * a mutex that is held elsewhere while calling synchronize_srcu() or
+ * synchronize_srcu_expedited().  But if you want lockdep to help you
+ * keep this stuff straight, you should instead use srcu_read_lock().
+ *
+ * The semaphore-like nature of srcu_down_read() means that the matching
+ * srcu_up_read() can be invoked from some other context, for example,
+ * from some other task or from an irq handler.  However, neither
+ * srcu_down_read() nor srcu_up_read() may be invoked from an NMI handler.
+ *
+ * Calls to srcu_down_read() may be nested, similar to the manner in
+ * which calls to down_read() may be nested.
+ */
+static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp)
+{
+	WARN_ON_ONCE(in_nmi());
+	srcu_check_nmi_safety(ssp, false);
+	return __srcu_read_lock(ssp);
+}
+
 /**
  * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
  * @ssp: srcu_struct in which to unregister the old reader.
@@ -254,6 +282,23 @@ srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
 	__srcu_read_unlock(ssp, idx);
 }
 
+/**
+ * srcu_up_read - unregister a old reader from an SRCU-protected structure.
+ * @ssp: srcu_struct in which to unregister the old reader.
+ * @idx: return value from corresponding srcu_read_lock().
+ *
+ * Exit an SRCU read-side critical section, but not necessarily from
+ * the same context as the maching srcu_down_read().
+ */
+static inline void srcu_up_read(struct srcu_struct *ssp, int idx)
+	__releases(ssp)
+{
+	WARN_ON_ONCE(idx & ~0x1);
+	WARN_ON_ONCE(in_nmi());
+	srcu_check_nmi_safety(ssp, false);
+	__srcu_read_unlock(ssp, idx);
+}
+
 /**
  * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
  *

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
@@ -49,7 +49,7 @@ struct srcu_data {
 struct srcu_node {
 	spinlock_t __private lock;
 	unsigned long srcu_have_cbs[4];		/* GP seq for children having CBs, but only */
-						/*  if greater than ->srcu_gq_seq. */
+						/*  if greater than ->srcu_gp_seq. */
 	unsigned long srcu_data_have_cbs[4];	/* Which srcu_data structs have CBs for given GP? */
 	unsigned long srcu_gp_seq_needed_exp;	/* Furthest future exp GP. */
 	struct srcu_node *srcu_parent;		/* Next up in tree. */

diff --git a/init/Kconfig b/init/Kconfig
@@ -1865,7 +1865,6 @@ config PERF_EVENTS
 	default y if PROFILING
 	depends on HAVE_PERF_EVENTS
 	select IRQ_WORK
-	select SRCU
 	help
 	  Enable kernel support for various performance events provided
 	  by software and hardware.