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-rw-r--r--include/linux/filter.h2
-rw-r--r--include/linux/if_tap.h4
-rw-r--r--include/linux/input.h7
-rw-r--r--include/linux/irq.h2
-rw-r--r--include/linux/irqchip/arm-gic-v3.h2
-rw-r--r--include/linux/key.h47
-rw-r--r--include/linux/mbus.h4
-rw-r--r--include/linux/mlx5/port.h2
-rw-r--r--include/linux/mm_types.h3
-rw-r--r--include/linux/mod_devicetable.h3
-rw-r--r--include/linux/netdevice.h3
-rw-r--r--include/linux/pm_qos.h8
-rw-r--r--include/linux/rculist.h2
-rw-r--r--include/linux/rcupdate.h22
-rw-r--r--include/linux/sched/mm.h16
-rw-r--r--include/linux/sctp.h34
-rw-r--r--include/linux/srcu.h1
-rw-r--r--include/linux/swait.h27
18 files changed, 126 insertions, 63 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h
index d29e58fde364..818a0b26249e 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -728,7 +728,7 @@ void xdp_do_flush_map(void);
void bpf_warn_invalid_xdp_action(u32 act);
void bpf_warn_invalid_xdp_redirect(u32 ifindex);
-struct sock *do_sk_redirect_map(void);
+struct sock *do_sk_redirect_map(struct sk_buff *skb);
#ifdef CONFIG_BPF_JIT
extern int bpf_jit_enable;
diff --git a/include/linux/if_tap.h b/include/linux/if_tap.h
index 4837157da0dc..9ae41cdd0d4c 100644
--- a/include/linux/if_tap.h
+++ b/include/linux/if_tap.h
@@ -73,8 +73,8 @@ void tap_del_queues(struct tap_dev *tap);
int tap_get_minor(dev_t major, struct tap_dev *tap);
void tap_free_minor(dev_t major, struct tap_dev *tap);
int tap_queue_resize(struct tap_dev *tap);
-int tap_create_cdev(struct cdev *tap_cdev,
- dev_t *tap_major, const char *device_name);
+int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
+ const char *device_name, struct module *module);
void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev);
#endif /*_LINUX_IF_TAP_H_*/
diff --git a/include/linux/input.h b/include/linux/input.h
index fb5e23c7ed98..7c7516eb7d76 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -234,6 +234,10 @@ struct input_dev {
#error "SW_MAX and INPUT_DEVICE_ID_SW_MAX do not match"
#endif
+#if INPUT_PROP_MAX != INPUT_DEVICE_ID_PROP_MAX
+#error "INPUT_PROP_MAX and INPUT_DEVICE_ID_PROP_MAX do not match"
+#endif
+
#define INPUT_DEVICE_ID_MATCH_DEVICE \
(INPUT_DEVICE_ID_MATCH_BUS | INPUT_DEVICE_ID_MATCH_VENDOR | INPUT_DEVICE_ID_MATCH_PRODUCT)
#define INPUT_DEVICE_ID_MATCH_DEVICE_AND_VERSION \
@@ -469,6 +473,9 @@ int input_get_keycode(struct input_dev *dev, struct input_keymap_entry *ke);
int input_set_keycode(struct input_dev *dev,
const struct input_keymap_entry *ke);
+bool input_match_device_id(const struct input_dev *dev,
+ const struct input_device_id *id);
+
void input_enable_softrepeat(struct input_dev *dev, int delay, int period);
extern struct class input_class;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index d4728bf6a537..5ad10948ea95 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1009,7 +1009,7 @@ void irq_gc_mask_clr_bit(struct irq_data *d);
void irq_gc_unmask_enable_reg(struct irq_data *d);
void irq_gc_ack_set_bit(struct irq_data *d);
void irq_gc_ack_clr_bit(struct irq_data *d);
-void irq_gc_mask_disable_reg_and_ack(struct irq_data *d);
+void irq_gc_mask_disable_and_ack_set(struct irq_data *d);
void irq_gc_eoi(struct irq_data *d);
int irq_gc_set_wake(struct irq_data *d, unsigned int on);
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 1ea576c8126f..14b74f22d43c 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -372,6 +372,8 @@
#define GITS_BASER_ENTRY_SIZE_SHIFT (48)
#define GITS_BASER_ENTRY_SIZE(r) ((((r) >> GITS_BASER_ENTRY_SIZE_SHIFT) & 0x1f) + 1)
#define GITS_BASER_ENTRY_SIZE_MASK GENMASK_ULL(52, 48)
+#define GITS_BASER_PHYS_52_to_48(phys) \
+ (((phys) & GENMASK_ULL(47, 16)) | (((phys) >> 48) & 0xf) << 12)
#define GITS_BASER_SHAREABILITY_SHIFT (10)
#define GITS_BASER_InnerShareable \
GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable)
diff --git a/include/linux/key.h b/include/linux/key.h
index e315e16b6ff8..8a15cabe928d 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -138,6 +138,11 @@ struct key_restriction {
struct key_type *keytype;
};
+enum key_state {
+ KEY_IS_UNINSTANTIATED,
+ KEY_IS_POSITIVE, /* Positively instantiated */
+};
+
/*****************************************************************************/
/*
* authentication token / access credential / keyring
@@ -169,6 +174,7 @@ struct key {
* - may not match RCU dereferenced payload
* - payload should contain own length
*/
+ short state; /* Key state (+) or rejection error (-) */
#ifdef KEY_DEBUGGING
unsigned magic;
@@ -176,18 +182,16 @@ struct key {
#endif
unsigned long flags; /* status flags (change with bitops) */
-#define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
-#define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
-#define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
-#define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
-#define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
-#define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
-#define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */
-#define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */
-#define KEY_FLAG_BUILTIN 8 /* set if key is built in to the kernel */
-#define KEY_FLAG_ROOT_CAN_INVAL 9 /* set if key can be invalidated by root without permission */
-#define KEY_FLAG_KEEP 10 /* set if key should not be removed */
-#define KEY_FLAG_UID_KEYRING 11 /* set if key is a user or user session keyring */
+#define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
+#define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
+#define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
+#define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
+#define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
+#define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
+#define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
+#define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
+#define KEY_FLAG_KEEP 8 /* set if key should not be removed */
+#define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
/* the key type and key description string
* - the desc is used to match a key against search criteria
@@ -213,7 +217,6 @@ struct key {
struct list_head name_link;
struct assoc_array keys;
};
- int reject_error;
};
/* This is set on a keyring to restrict the addition of a link to a key
@@ -353,17 +356,27 @@ extern void key_set_timeout(struct key *, unsigned);
#define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
#define KEY_NEED_ALL 0x3f /* All the above permissions */
+static inline short key_read_state(const struct key *key)
+{
+ /* Barrier versus mark_key_instantiated(). */
+ return smp_load_acquire(&key->state);
+}
+
/**
- * key_is_instantiated - Determine if a key has been positively instantiated
+ * key_is_positive - Determine if a key has been positively instantiated
* @key: The key to check.
*
* Return true if the specified key has been positively instantiated, false
* otherwise.
*/
-static inline bool key_is_instantiated(const struct key *key)
+static inline bool key_is_positive(const struct key *key)
+{
+ return key_read_state(key) == KEY_IS_POSITIVE;
+}
+
+static inline bool key_is_negative(const struct key *key)
{
- return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
- !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
+ return key_read_state(key) < 0;
}
#define dereference_key_rcu(KEY) \
diff --git a/include/linux/mbus.h b/include/linux/mbus.h
index 0d3f14fd2621..4773145246ed 100644
--- a/include/linux/mbus.h
+++ b/include/linux/mbus.h
@@ -31,8 +31,8 @@ struct mbus_dram_target_info
struct mbus_dram_window {
u8 cs_index;
u8 mbus_attr;
- u32 base;
- u32 size;
+ u64 base;
+ u64 size;
} cs[4];
};
diff --git a/include/linux/mlx5/port.h b/include/linux/mlx5/port.h
index c57d4b7de3a8..c59af8ab753a 100644
--- a/include/linux/mlx5/port.h
+++ b/include/linux/mlx5/port.h
@@ -157,6 +157,8 @@ int mlx5_set_port_prio_tc(struct mlx5_core_dev *mdev, u8 *prio_tc);
int mlx5_query_port_prio_tc(struct mlx5_core_dev *mdev,
u8 prio, u8 *tc);
int mlx5_set_port_tc_group(struct mlx5_core_dev *mdev, u8 *tc_group);
+int mlx5_query_port_tc_group(struct mlx5_core_dev *mdev,
+ u8 tc, u8 *tc_group);
int mlx5_set_port_tc_bw_alloc(struct mlx5_core_dev *mdev, u8 *tc_bw);
int mlx5_query_port_tc_bw_alloc(struct mlx5_core_dev *mdev,
u8 tc, u8 *bw_pct);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 46f4ecf5479a..1861ea8dba77 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -445,6 +445,9 @@ struct mm_struct {
unsigned long flags; /* Must use atomic bitops to access the bits */
struct core_state *core_state; /* coredumping support */
+#ifdef CONFIG_MEMBARRIER
+ atomic_t membarrier_state;
+#endif
#ifdef CONFIG_AIO
spinlock_t ioctx_lock;
struct kioctx_table __rcu *ioctx_table;
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 694cebb50f72..2657f9f51536 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -293,6 +293,7 @@ struct pcmcia_device_id {
#define INPUT_DEVICE_ID_SND_MAX 0x07
#define INPUT_DEVICE_ID_FF_MAX 0x7f
#define INPUT_DEVICE_ID_SW_MAX 0x0f
+#define INPUT_DEVICE_ID_PROP_MAX 0x1f
#define INPUT_DEVICE_ID_MATCH_BUS 1
#define INPUT_DEVICE_ID_MATCH_VENDOR 2
@@ -308,6 +309,7 @@ struct pcmcia_device_id {
#define INPUT_DEVICE_ID_MATCH_SNDBIT 0x0400
#define INPUT_DEVICE_ID_MATCH_FFBIT 0x0800
#define INPUT_DEVICE_ID_MATCH_SWBIT 0x1000
+#define INPUT_DEVICE_ID_MATCH_PROPBIT 0x2000
struct input_device_id {
@@ -327,6 +329,7 @@ struct input_device_id {
kernel_ulong_t sndbit[INPUT_DEVICE_ID_SND_MAX / BITS_PER_LONG + 1];
kernel_ulong_t ffbit[INPUT_DEVICE_ID_FF_MAX / BITS_PER_LONG + 1];
kernel_ulong_t swbit[INPUT_DEVICE_ID_SW_MAX / BITS_PER_LONG + 1];
+ kernel_ulong_t propbit[INPUT_DEVICE_ID_PROP_MAX / BITS_PER_LONG + 1];
kernel_ulong_t driver_info;
};
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f535779d9dc1..2eaac7d75af4 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3694,6 +3694,9 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
unsigned char name_assign_type,
void (*setup)(struct net_device *),
unsigned int txqs, unsigned int rxqs);
+int dev_get_valid_name(struct net *net, struct net_device *dev,
+ const char *name);
+
#define alloc_netdev(sizeof_priv, name, name_assign_type, setup) \
alloc_netdev_mqs(sizeof_priv, name, name_assign_type, setup, 1, 1)
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 032b55909145..d68b0569a5eb 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -27,16 +27,17 @@ enum pm_qos_flags_status {
PM_QOS_FLAGS_ALL,
};
-#define PM_QOS_DEFAULT_VALUE -1
+#define PM_QOS_DEFAULT_VALUE (-1)
+#define PM_QOS_LATENCY_ANY S32_MAX
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
#define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
#define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0
+#define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT PM_QOS_LATENCY_ANY
#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0
#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1)
-#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
#define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
#define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1)
@@ -174,7 +175,8 @@ static inline s32 dev_pm_qos_requested_flags(struct device *dev)
static inline s32 dev_pm_qos_raw_read_value(struct device *dev)
{
return IS_ERR_OR_NULL(dev->power.qos) ?
- 0 : pm_qos_read_value(&dev->power.qos->resume_latency);
+ PM_QOS_RESUME_LATENCY_NO_CONSTRAINT :
+ pm_qos_read_value(&dev->power.qos->resume_latency);
}
#else
static inline enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev,
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index b1fd8bf85fdc..2bea1d5e9930 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -276,7 +276,7 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
#define list_entry_rcu(ptr, type, member) \
container_of(lockless_dereference(ptr), type, member)
-/**
+/*
* Where are list_empty_rcu() and list_first_entry_rcu()?
*
* Implementing those functions following their counterparts list_empty() and
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index de50d8a4cf41..1a9f70d44af9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -523,7 +523,7 @@ static inline void rcu_preempt_sleep_check(void) { }
* Return the value of the specified RCU-protected pointer, but omit
* both the smp_read_barrier_depends() and the READ_ONCE(). This
* is useful in cases where update-side locks prevent the value of the
- * pointer from changing. Please note that this primitive does -not-
+ * pointer from changing. Please note that this primitive does *not*
* prevent the compiler from repeating this reference or combining it
* with other references, so it should not be used without protection
* of appropriate locks.
@@ -568,7 +568,7 @@ static inline void rcu_preempt_sleep_check(void) { }
* is handed off from RCU to some other synchronization mechanism, for
* example, reference counting or locking. In C11, it would map to
* kill_dependency(). It could be used as follows:
- *
+ * ``
* rcu_read_lock();
* p = rcu_dereference(gp);
* long_lived = is_long_lived(p);
@@ -579,6 +579,7 @@ static inline void rcu_preempt_sleep_check(void) { }
* p = rcu_pointer_handoff(p);
* }
* rcu_read_unlock();
+ *``
*/
#define rcu_pointer_handoff(p) (p)
@@ -778,18 +779,21 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
/**
* RCU_INIT_POINTER() - initialize an RCU protected pointer
+ * @p: The pointer to be initialized.
+ * @v: The value to initialized the pointer to.
*
* Initialize an RCU-protected pointer in special cases where readers
* do not need ordering constraints on the CPU or the compiler. These
* special cases are:
*
- * 1. This use of RCU_INIT_POINTER() is NULLing out the pointer -or-
+ * 1. This use of RCU_INIT_POINTER() is NULLing out the pointer *or*
* 2. The caller has taken whatever steps are required to prevent
- * RCU readers from concurrently accessing this pointer -or-
+ * RCU readers from concurrently accessing this pointer *or*
* 3. The referenced data structure has already been exposed to
- * readers either at compile time or via rcu_assign_pointer() -and-
- * a. You have not made -any- reader-visible changes to
- * this structure since then -or-
+ * readers either at compile time or via rcu_assign_pointer() *and*
+ *
+ * a. You have not made *any* reader-visible changes to
+ * this structure since then *or*
* b. It is OK for readers accessing this structure from its
* new location to see the old state of the structure. (For
* example, the changes were to statistical counters or to
@@ -805,7 +809,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
* by a single external-to-structure RCU-protected pointer, then you may
* use RCU_INIT_POINTER() to initialize the internal RCU-protected
* pointers, but you must use rcu_assign_pointer() to initialize the
- * external-to-structure pointer -after- you have completely initialized
+ * external-to-structure pointer *after* you have completely initialized
* the reader-accessible portions of the linked structure.
*
* Note that unlike rcu_assign_pointer(), RCU_INIT_POINTER() provides no
@@ -819,6 +823,8 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
/**
* RCU_POINTER_INITIALIZER() - statically initialize an RCU protected pointer
+ * @p: The pointer to be initialized.
+ * @v: The value to initialized the pointer to.
*
* GCC-style initialization for an RCU-protected pointer in a structure field.
*/
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index ae53e413fb13..ab9bf7b73954 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -211,4 +211,20 @@ static inline void memalloc_noreclaim_restore(unsigned int flags)
current->flags = (current->flags & ~PF_MEMALLOC) | flags;
}
+#ifdef CONFIG_MEMBARRIER
+enum {
+ MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
+ MEMBARRIER_STATE_SWITCH_MM = (1U << 1),
+};
+
+static inline void membarrier_execve(struct task_struct *t)
+{
+ atomic_set(&t->mm->membarrier_state, 0);
+}
+#else
+static inline void membarrier_execve(struct task_struct *t)
+{
+}
+#endif
+
#endif /* _LINUX_SCHED_MM_H */
diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index 82b171e1aa0b..da803dfc7a39 100644
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -231,7 +231,7 @@ struct sctp_datahdr {
__be32 tsn;
__be16 stream;
__be16 ssn;
- __be32 ppid;
+ __u32 ppid;
__u8 payload[0];
};
@@ -716,28 +716,28 @@ struct sctp_reconf_chunk {
struct sctp_strreset_outreq {
struct sctp_paramhdr param_hdr;
- __u32 request_seq;
- __u32 response_seq;
- __u32 send_reset_at_tsn;
- __u16 list_of_streams[0];
+ __be32 request_seq;
+ __be32 response_seq;
+ __be32 send_reset_at_tsn;
+ __be16 list_of_streams[0];
};
struct sctp_strreset_inreq {
struct sctp_paramhdr param_hdr;
- __u32 request_seq;
- __u16 list_of_streams[0];
+ __be32 request_seq;
+ __be16 list_of_streams[0];
};
struct sctp_strreset_tsnreq {
struct sctp_paramhdr param_hdr;
- __u32 request_seq;
+ __be32 request_seq;
};
struct sctp_strreset_addstrm {
struct sctp_paramhdr param_hdr;
- __u32 request_seq;
- __u16 number_of_streams;
- __u16 reserved;
+ __be32 request_seq;
+ __be16 number_of_streams;
+ __be16 reserved;
};
enum {
@@ -752,16 +752,16 @@ enum {
struct sctp_strreset_resp {
struct sctp_paramhdr param_hdr;
- __u32 response_seq;
- __u32 result;
+ __be32 response_seq;
+ __be32 result;
};
struct sctp_strreset_resptsn {
struct sctp_paramhdr param_hdr;
- __u32 response_seq;
- __u32 result;
- __u32 senders_next_tsn;
- __u32 receivers_next_tsn;
+ __be32 response_seq;
+ __be32 result;
+ __be32 senders_next_tsn;
+ __be32 receivers_next_tsn;
};
#endif /* __LINUX_SCTP_H__ */
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 39af9bc0f653..62be8966e837 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -78,6 +78,7 @@ void synchronize_srcu(struct srcu_struct *sp);
/**
* srcu_read_lock_held - might we be in SRCU read-side critical section?
+ * @sp: The srcu_struct structure to check
*
* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
diff --git a/include/linux/swait.h b/include/linux/swait.h
index 73e97a08d3d0..cf30f5022472 100644
--- a/include/linux/swait.h
+++ b/include/linux/swait.h
@@ -9,13 +9,16 @@
/*
* Simple wait queues
*
- * While these are very similar to the other/complex wait queues (wait.h) the
- * most important difference is that the simple waitqueue allows for
- * deterministic behaviour -- IOW it has strictly bounded IRQ and lock hold
- * times.
+ * While these are very similar to regular wait queues (wait.h) the most
+ * important difference is that the simple waitqueue allows for deterministic
+ * behaviour -- IOW it has strictly bounded IRQ and lock hold times.
*
- * In order to make this so, we had to drop a fair number of features of the
- * other waitqueue code; notably:
+ * Mainly, this is accomplished by two things. Firstly not allowing swake_up_all
+ * from IRQ disabled, and dropping the lock upon every wakeup, giving a higher
+ * priority task a chance to run.
+ *
+ * Secondly, we had to drop a fair number of features of the other waitqueue
+ * code; notably:
*
* - mixing INTERRUPTIBLE and UNINTERRUPTIBLE sleeps on the same waitqueue;
* all wakeups are TASK_NORMAL in order to avoid O(n) lookups for the right
@@ -24,12 +27,14 @@
* - the exclusive mode; because this requires preserving the list order
* and this is hard.
*
- * - custom wake functions; because you cannot give any guarantees about
- * random code.
- *
- * As a side effect of this; the data structures are slimmer.
+ * - custom wake callback functions; because you cannot give any guarantees
+ * about random code. This also allows swait to be used in RT, such that
+ * raw spinlock can be used for the swait queue head.
*
- * One would recommend using this wait queue where possible.
+ * As a side effect of these; the data structures are slimmer albeit more ad-hoc.
+ * For all the above, note that simple wait queues should _only_ be used under
+ * very specific realtime constraints -- it is best to stick with the regular
+ * wait queues in most cases.
*/
struct task_struct;