Re: [PATCH v2] Documentation/locking/locktypes: minor copy editor fixes
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: 2020-03-26 02:40:44
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linux-acpi, linux-pci, linux-pm, linux-usb, linux-wireless, lkml, netdev, platform-driver-x86
On Wed, Mar 25, 2020 at 09:58:14AM -0700, Randy Dunlap wrote:
From: Randy Dunlap <redacted> Minor editorial fixes: - add some hyphens in multi-word adjectives - add some periods for consistency - add "'" for possessive CPU's - capitalize IRQ when it's an acronym and not part of a function name Signed-off-by: Randy Dunlap <redacted> Cc: Paul McKenney <paulmck@kernel.org> Cc: Thomas Gleixner <redacted> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Joel Fernandes <redacted> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>
Some nits below, but with or without those suggested changes: Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
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--- Documentation/locking/locktypes.rst | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)--- linux-next-20200325.orig/Documentation/locking/locktypes.rst +++ linux-next-20200325/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-enabled kernels due to preemption and
Or just drop the " enabled".
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interrupt disabled sections. PI clearly cannot preempt preemption-disabled or interrupt-disabled@@ -150,7 +150,7 @@ kernel configuration including PREEMPT_R 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 +On a non-PREEMPT_RT-enabled kernel spinlock_t is mapped to raw_spinlock_t
Ditto.
and has exactly the same semantics. spinlock_t and PREEMPT_RT ------------------------- -On a PREEMPT_RT enabled kernel spinlock_t is mapped to a separate +On a PREEMPT_RT-enabled kernel spinlock_t is mapped to a separate
And here as well.
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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.@@ -279,7 +279,7 @@ fully preemptible context. Instead, use 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, +allowing things like per-CPU IRQ-disabled locks to be acquired. However,
Quite a bit of text in the kernel uses "irq", lower case. Another option is to spell out "interrupt".
this approach should be used only where absolutely necessary.