Date: Thu, 2 Sep 2010 11:41:16 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: David Xu <davidxu@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212076 - head/lib/libthr/thread Message-ID: <20100902084116.GJ2396@deviant.kiev.zoral.com.ua> In-Reply-To: <4C7FD232.9080100@freebsd.org> References: <201009010218.o812IX5G048257@svn.freebsd.org> <20100902081136.GG2396@deviant.kiev.zoral.com.ua> <4C7FD232.9080100@freebsd.org>
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--7SYzLFxCLxOg+UP5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 02, 2010 at 04:34:58PM +0000, David Xu wrote: > Kostik Belousov wrote: > >On Wed, Sep 01, 2010 at 02:18:33AM +0000, David Xu wrote: > >>Author: davidxu > >>Date: Wed Sep 1 02:18:33 2010 > >>New Revision: 212076 > >>URL: http://svn.freebsd.org/changeset/base/212076 > >> > >>Log: > >> Add signal handler wrapper, the reason to add it becauses there are > >> some cases we want to improve: > >> 1) if a thread signal got a signal while in cancellation point, > >> it is possible the TDP_WAKEUP may be eaten by signal handler > >> if the handler called some interruptibly system calls. > >> 2) In signal handler, we want to disable cancellation. > >> 3) When thread holding some low level locks, it is better to > >> disable signal, those code need not to worry reentrancy, > >> sigprocmask system call is avoided because it is a bit expensive. > >> The signal handler wrapper works in this way: > >> 1) libthr installs its signal handler if user code invokes sigaction > >> to install its handler, the user handler is recorded in internal > >> array. > >> 2) when a signal is delivered, libthr's signal handler is invoke, > >> libthr checks if thread holds some low level lock or is in criti= cal > >> region, if it is true, the signal is buffered, and all signals a= re > >> masked, once the thread leaves critical region, correct signal > >> mask is restored and buffered signal is processed. > >> 3) before user signal handler is invoked, cancellation is temporari= ly > >> disabled, after user signal handler is returned, cancellation st= ate > >> is restored, and pending cancellation is rescheduled. > > > >>+static void > >>+thr_sighandler(int sig, siginfo_t *info, void *_ucp) > >>+{ > > > >>+ if ((actp->sa_flags & SA_SIGINFO) !=3D 0) > >>+ (*(sigfunc))(sig, info, ucp); > >>+ else { > >>+ ((ohandler)(*sigfunc))( > >>+ sig, info->si_code, (struct sigcontext *)ucp, > >>+ info->si_addr, (__sighandler_t *)sigfunc); > >>+ } > > > >I do not think this is very important, but freebsd old-style signal > >handler fourth argument is usually the faulted %eip value. This is > >most likely irrelevant for any source that is linked with libthr.so > >new enough to contain this change. >=20 > Isn't the si_addr in siginfo a fault address ? I remembered I saved > the fault address in ksiginfo_t which is converted to userland > siginfo, and fault address should be there. what's wrong here ? >=20 Oops, sorry, I miscalculated the position of the arguments :(. --7SYzLFxCLxOg+UP5 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkx/YywACgkQC3+MBN1Mb4i/9wCglYCkDv4JoFnRTFhmrdJXOfmx 8+8AoKhvH9n0ZUs2Co+PnmbAVS691mDx =dBtf -----END PGP SIGNATURE----- --7SYzLFxCLxOg+UP5--
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