On Fri, 1 Mar 2024 13:37:18 +0800 linke <lilink...@qq.com> wrote: > > So basically you are worried about read-tearing? > > > > That wasn't mentioned in the change log. > > Yes. Sorry for making this confused, I am not very familiar with this and > still learning.
No problem. We all have to learn this anyway. > > > Funny part is, if the above timestamp read did a tear, then this would > > definitely not match, and would return the correct value. That is, the > > buffer is not empty because the only way for this to get corrupted is if > > something is in the process of writing to it. > > I agree with you here. > > commit = rb_page_commit(commit_page); > > But if commit_page above is the result of a torn read, the commit field > read by rb_page_commit() may not represent a valid value. But commit_page is a word length, and I will argue that any compiler that tears "long" words is broken. ;-) > > In this case, READ_ONCE() is only needed for the commit_page. But we can at least keep the READ_ONCE() on the commit_page just because it is used in the next instruction. -- Steve
