cvs commit: src/sys/kern kern_sig.c

[Simon 'corecode' Schubert]

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.

cheers
 simon
--
Serve - BSD     +++  RENT this banner advert  +++    ASCII Ribbon   /"\
Work - Mac      +++  space for low €€€ NOW!1  +++      Campaign     \ /
Party Enjoy Relax   |   http://dragonflybsd.org      Against  HTML   \
Dude 2c 2 the max   !   http://golden-apple.biz       Mail + News   / \
Attachment:
signature.asc
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pgp00008.pgp
Type: application/octet-stream
Size: 252 bytes
Desc: "Description: OpenPGP digital signature"
URL: <http://lists.dragonflybsd.org/pipermail/commits/attachments/20070222/ec8d7057/attachment-0020.obj>