DragonFly commits List (threaded) for 2007-02
DragonFly BSD
DragonFly commits List (threaded) for 2007-02
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Re: cvs commit: src/sys/kern kern_sig.c

From: "Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>
Date: Thu, 22 Feb 2007 19:49:19 +0100

Matthew Dillon wrote:
:corecode 2007/02/22 07:48:55 PST
:DragonFly src repository
: Modified files:
: sys/kern kern_sig.c : Log:
: Fix stopping of the current process, which was broken by the last commit.
: : If the current process is still far inside the kernel and is going to
: tsleep(), CURSIG()/issignal() in tsleep() have to see the pending signal;

You can't actually stop a process in tsleep, ever. The kernel might
be holding resources (such as lockmgr locks) that would never be released.

A process can only be stopped in userret() (platform/pc32/i386/trap.c).

Please make sure that those semantics are retained.

That always happened. CURSIG/issignal check for a SA_STOP signal and calls tstop, which in turn calls tsleep() in a loop until SSTOP (previously P_STOPPED) is cleared.

I'm also not fond of this, but seems the kernel code assumes this behaviour. I noticed this in ttread(): it calls ttysleep()/tsleep(), but really expects the thread to be stopped *inside*.

I'd rather have the threads stop only in userret() as well (and possibly when entering the kernel), but we'd need very careful audit of CURSIG/issignal() users.


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