| epoch.9 (7739f6e5ad31a5018e05775101dc1ebddff5c7c0) | epoch.9 (68195696a6e7bfd7e14e1ee20d69b48c97abd8fc) |
|---|---|
| 1.\" 2.\" Copyright (C) 2018 Matthew Macy <mmacy@FreeBSD.org>. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 35 unchanged lines hidden (view full) --- 44.In sys/param.h 45.In sys/proc.h 46.In sys/epoch.h 47.Ft epoch_t 48.Fn epoch_alloc "int flags" 49.Ft void 50.Fn epoch_enter "epoch_t epoch" 51.Ft void | 1.\" 2.\" Copyright (C) 2018 Matthew Macy <mmacy@FreeBSD.org>. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 35 unchanged lines hidden (view full) --- 44.In sys/param.h 45.In sys/proc.h 46.In sys/epoch.h 47.Ft epoch_t 48.Fn epoch_alloc "int flags" 49.Ft void 50.Fn epoch_enter "epoch_t epoch" 51.Ft void |
| 52.Fn epoch_enter_preempt "epoch_t epoch" | 52.Fn epoch_enter_preempt "epoch_t epoch" "epoch_tracker_t et" |
| 53.Ft void 54.Fn epoch_exit "epoch_t epoch" 55.Ft void | 53.Ft void 54.Fn epoch_exit "epoch_t epoch" 55.Ft void |
| 56.Fn epoch_exit_preempt "epoch_t epoch" | 56.Fn epoch_exit_preempt "epoch_t epoch" "epoch_tracker_t et" |
| 57.Ft void 58.Fn epoch_wait "epoch_t epoch" 59.Ft void 60.Fn epoch_wait_preempt "epoch_t epoch" 61.Ft void 62.Fn epoch_call "epoch_t epoch" "epoch_context_t ctx" "void (*callback) (epoch_context_t)" 63.Ft int 64.Fn in_epoch "void" --- 34 unchanged lines hidden (view full) --- 99Only non-sleepable locks can be acquired during a section protected by 100.Fn epoch_enter_preempt 101and 102.Fn epoch_exit_preempt . 103INVARIANTS can assert that a thread is in an epoch by using 104.Fn in_epoch . 105.Pp 106The epoch API currently does not support sleeping in epoch_preempt sections. | 57.Ft void 58.Fn epoch_wait "epoch_t epoch" 59.Ft void 60.Fn epoch_wait_preempt "epoch_t epoch" 61.Ft void 62.Fn epoch_call "epoch_t epoch" "epoch_context_t ctx" "void (*callback) (epoch_context_t)" 63.Ft int 64.Fn in_epoch "void" --- 34 unchanged lines hidden (view full) --- 99Only non-sleepable locks can be acquired during a section protected by 100.Fn epoch_enter_preempt 101and 102.Fn epoch_exit_preempt . 103INVARIANTS can assert that a thread is in an epoch by using 104.Fn in_epoch . 105.Pp 106The epoch API currently does not support sleeping in epoch_preempt sections. |
| 107A caller cannot do epoch_enter recursively on different preemptible epochs. | |
| 108A caller should never call 109.Fn epoch_wait | 107A caller should never call 108.Fn epoch_wait |
| 110in the middle of an epoch section as this will lead to a deadlock. | 109in the middle of an epoch section for the same epoch as this will lead to a deadlock. |
| 111.Pp | 110.Pp |
| 112Note that epochs are not a straight replacement for read locks. | 111Be default mutexes cannot be held across 112.Fn epoch_wait_preempt . 113To permit this the epoch must be allocated with 114.Fn EPOCH_LOCKED . 115When doing this one must be cautious of creating a situation where a deadlock is 116possible. Note that epochs are not a straight replacement for read locks. |
| 113Callers must use safe list and tailq traversal routines in an epoch (see ck_queue). 114When modifying a list referenced from an epoch section safe removal 115routines must be used and the caller can no longer modify a list entry 116in place. 117An item to be modified must be handled with copy on write 118and frees must be deferred until after a grace period has elapsed. 119.Sh RETURN VALUES 120.Fn in_epoch --- 73 unchanged lines hidden --- | 117Callers must use safe list and tailq traversal routines in an epoch (see ck_queue). 118When modifying a list referenced from an epoch section safe removal 119routines must be used and the caller can no longer modify a list entry 120in place. 121An item to be modified must be handled with copy on write 122and frees must be deferred until after a grace period has elapsed. 123.Sh RETURN VALUES 124.Fn in_epoch --- 73 unchanged lines hidden --- |