diff options
Diffstat (limited to 'Documentation/locking')
| -rw-r--r-- | Documentation/locking/locktypes.rst | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/locking/locktypes.rst b/Documentation/locking/locktypes.rst index 1c18bb8785e2..09f45ce38d26 100644 --- a/Documentation/locking/locktypes.rst +++ b/Documentation/locking/locktypes.rst @@ -84,7 +84,7 @@ rtmutex RT-mutexes are mutexes with support for priority inheritance (PI). -PI has limitations on non PREEMPT_RT enabled kernels due to preemption and +PI has limitations on non-PREEMPT_RT kernels due to preemption and interrupt disabled sections. PI clearly cannot preempt preemption-disabled or interrupt-disabled @@ -150,7 +150,7 @@ kernel configuration including PREEMPT_RT enabled kernels. raw_spinlock_t is a strict spinning lock implementation in all kernels, including PREEMPT_RT kernels. Use raw_spinlock_t only in real critical -core code, low level interrupt handling and places where disabling +core code, low-level interrupt handling and places where disabling preemption or interrupts is required, for example, to safely access hardware state. raw_spinlock_t can sometimes also be used when the critical section is tiny, thus avoiding RT-mutex overhead. @@ -160,20 +160,20 @@ spinlock_t The semantics of spinlock_t change with the state of PREEMPT_RT. -On a non PREEMPT_RT enabled kernel spinlock_t is mapped to raw_spinlock_t -and has exactly the same semantics. +On a non-PREEMPT_RT kernel spinlock_t is mapped to raw_spinlock_t and has +exactly the same semantics. spinlock_t and PREEMPT_RT ------------------------- -On a PREEMPT_RT enabled kernel spinlock_t is mapped to a separate -implementation based on rt_mutex which changes the semantics: +On a PREEMPT_RT kernel spinlock_t is mapped to a separate implementation +based on rt_mutex which changes the semantics: - - Preemption is not disabled + - Preemption is not disabled. - The hard interrupt related suffixes for spin_lock / spin_unlock - operations (_irq, _irqsave / _irqrestore) do not affect the CPUs - interrupt disabled state + operations (_irq, _irqsave / _irqrestore) do not affect the CPU's + interrupt disabled state. - The soft interrupt related suffix (_bh()) still disables softirq handlers. @@ -279,8 +279,8 @@ fully preemptible context. Instead, use spin_lock_irq() or spin_lock_irqsave() and their unlock counterparts. In cases where the interrupt disabling and locking must remain separate, PREEMPT_RT offers a local_lock mechanism. Acquiring the local_lock pins the task to a CPU, -allowing things like per-CPU irq-disabled locks to be acquired. However, -this approach should be used only where absolutely necessary. +allowing things like per-CPU interrupt disabled locks to be acquired. +However, this approach should be used only where absolutely necessary. raw_spinlock_t |