On Fri, 6 Dec 2024 19:23:59 -0800, Randy Dunlap wrote: > Hi, > > Can someone explain what the (consistent) usage of '!' does in this file? > This is the only file in Documentation/ that uses this syntax. > > > E.g.: > >> diff --git a/Documentation/mm/process_addrs.rst b/Documentation/mm/process_addrs.rst >> index 81417fa2ed20..92cf497a9e3c 100644 >> --- a/Documentation/mm/process_addrs.rst >> +++ b/Documentation/mm/process_addrs.rst >> @@ -716,7 +716,11 @@ calls :c:func:`!rcu_read_lock` to ensure that the VMA is looked up in an RCU >> critical section, then attempts to VMA lock it via :c:func:`!vma_start_read`, >> before releasing the RCU lock via :c:func:`!rcu_read_unlock`. >> >> -VMA read locks hold the read lock on the :c:member:`!vma->vm_lock` semaphore for >> +In cases when the user already holds mmap read lock, :c:func:`!vma_start_read_locked` >> +and :c:func:`!vma_start_read_locked_nested` can be used. These functions always >> +succeed in acquiring VMA read lock. > Quoting from https://www.sphinx-doc.org/en/master/usage/referencing.html#syntax * Suppressed link: Prefixing with an exclamation mark (!) prevents the creation of a link but otherwise keeps the visual output of the role. For example, writing :py:func:`!target` displays target(), with no link generated. This is helpful for cases in which the link target does not exist; e.g. changelog entries that describe removed functionality, or third-party libraries that don’t support intersphinx. Suppressing the link prevents warnings in nitpicky mode. But in kernel documentation, there is a preferred alternative. Referencing by function names is the way to go. For example: calls rcu_read_lock() to ensure that the VMA is looked up in an RCU critical section, then attempts to VMA lock it via vma_start_read(), before releasing the RCU lock via rcu_read_unlock(). In cases when the user already holds mmap read lock, vma_start_read_locked() and vma_start_read_locked_nested() can be used. These functions always succeed in acquiring VMA read lock. They work regardless of link target's existence. Kernel-specific Sphinx extension named "automarkup" does conversions for you. HTH, Akira > thanks. > -- > ~Randy
