On Fri, Dec 6, 2024 at 8:24 PM Akira Yokosawa <akiyks@xxxxxxxxx> wrote: > > 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. Thanks for the information. I was simply following the same style the document was written in. Sounds like converting it to the preferred alternative in a separate patch would be best. Lorenzo, WDYT? > > HTH, Akira > > > thanks. > > -- > > ~Randy >
