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Documentation/locking/locktypes: Minor copy editor fixes 

Minor editorial fixes:
- remove 'enabled' from PREEMPT_RT enabled kernels for consistency
- add some periods for consistency
- add "'" for possessive CPU's
- spell out interrupts

[ tglx: Picked up Paul's suggestions ]

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lkml.kernel.org/r/ac615f36-0b44-408d-aeab-d76e4241add4@infradead.org
This commit is contained in:
Randy Dunlap 2020-03-25 09:58:14 -07:00 committed by Thomas Gleixner
parent 7ecc6aa522
commit 51e69e6551
1 changed files with 11 additions and 11 deletions
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22
Documentation/locking/locktypes.rst
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@ -84,7 +84,7 @@ rtmutex
RT-mutexes are mutexes with support for priority inheritance (PI). 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. interrupt disabled sections.
PI clearly cannot preempt preemption-disabled or interrupt-disabled 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, raw_spinlock_t is a strict spinning lock implementation in all kernels,
including PREEMPT_RT kernels. Use raw_spinlock_t only in real critical 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 preemption or interrupts is required, for example, to safely access
hardware state. raw_spinlock_t can sometimes also be used when the hardware state. raw_spinlock_t can sometimes also be used when the
critical section is tiny, thus avoiding RT-mutex overhead. 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. 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 On a non-PREEMPT_RT kernel spinlock_t is mapped to raw_spinlock_t and has
and has exactly the same semantics. exactly the same semantics.
spinlock_t and PREEMPT_RT spinlock_t and PREEMPT_RT
------------------------- -------------------------
On a PREEMPT_RT enabled kernel spinlock_t is mapped to a separate On a PREEMPT_RT kernel spinlock_t is mapped to a separate implementation
implementation based on rt_mutex which changes the semantics: 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 - The hard interrupt related suffixes for spin_lock / spin_unlock
operations (_irq, _irqsave / _irqrestore) do not affect the CPUs operations (_irq, _irqsave / _irqrestore) do not affect the CPU's
interrupt disabled state interrupt disabled state.
- The soft interrupt related suffix (_bh()) still disables softirq - The soft interrupt related suffix (_bh()) still disables softirq
handlers. 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 spin_lock_irqsave() and their unlock counterparts. In cases where the
interrupt disabling and locking must remain separate, PREEMPT_RT offers a interrupt disabling and locking must remain separate, PREEMPT_RT offers a
local_lock mechanism. Acquiring the local_lock pins the task to a CPU, 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, allowing things like per-CPU interrupt disabled locks to be acquired.
this approach should be used only where absolutely necessary. However, this approach should be used only where absolutely necessary.
raw_spinlock_t raw_spinlock_t