From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Date: Tue, 08 Apr 2008 11:35:19 +0000 Subject: Re: [PATCH 2/4] set_restore_sigmask TIF_SIGPENDING Message-Id: <20080408113519.GA227@tv-sign.ru> List-Id: References: <20080329001230.D013726FA1D@magilla.localdomain> <20080329001341.7F93826FA1D@magilla.localdomain> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Linus Torvalds Cc: Roland McGrath , Andrew Morton , Martin Schwidefsky , linux-s390@vger.kernel.org, tony.luck@intel.com, linux-ia64@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Roland, Linus, I'm sorry for being offtopic, but there is something I can't understand from the very beginning, when TIF_RESTORE_SIGMASK was introduced. On 03/28, Linus Torvalds wrote: > > On Fri, 28 Mar 2008, Roland McGrath wrote: > > > > Set TIF_SIGPENDING in set_restore_sigmask. This lets arch code take > > TIF_RESTORE_SIGMASK out of the set of bits that will be noticed on > > return to user mode. On some machines those bits are scarce, and we > > can free this unneeded one up for other uses. > > Hmm. That probably means that TIF_RESTORE_SIGMASK shouldn't be a "TIF" > flag at all, Yes! > but a "TS" ("thread status") flag. Why do we need any flag? It looks a bit ugly. Isn't it better to introduce the new magic ERESTART_XXX which means ERESTARTNOHAND + restore-sigmask ? We only need this flag as an implicit parameter to the arch dependent do_signal() which we can't call directly, and thus it must imply TIF_SIGPENDING, and it is not valid after do_signal() (should be cleared). This all looks like ERESTART_ magic, why should we add something else ? See also http://marc.info/?l=linux-kernel&m3734458516136 Of course, probably it is too late to change the implementation even if I am right, the question is: what I am missed? Oleg.