Messages in this thread | | | Date | Sat, 12 Jul 2008 10:41:39 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] x86_64: fix delayed signals |
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On Sat, 12 Jul 2008, Andi Kleen wrote: > > Linus, the fact that is not explained by your theory is why > Ctrl-Z+kill works but Ctrl-C doesn't.
Umm. Read the reports more carefully. Many of the complaints are about ^Z too.
More-over, ^Z and ^C are very different from an app standpoint. A _lot_ of applications block or catch ^C (SIGINT), while doing the same for ^Z (SIGTSTP) and SIGTERM is much less common (but possible: a tty sends SIGTSTP, which is blockable, not SIGSTOP, which is not).
The reason? It's quite common to catch ^C in order to do cleanup. The common handler case is that you catch SIGINT, do cleanup, and then kill yourself with SIGINT in order to make it _look_ like you reacted directly to the ^C.
So there are a _lot_ of loads where ^C will not kill things immediately, but ^Z + SIGKILL (or SIGTERM, the default for "sig") will.
Try doing a "yum update", for example.
Or use 'git', for that matter. git does exactly that kind of thing: catches SIGINT and removes temp-files etc. But if you kill it manually using some "stronger" signal (and using ^Z to get the shell back before you do that is obviously one way), that won't happen.
And trust me, git is not at all unusual in this respect.
Linus
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