[ECOS] TCP/IP preemption fix

Grant Edwards grante@visi.com
Thu Apr 13 14:29:00 GMT 2000

On Wed, Apr 12, 2000 at 06:13:04PM -0600, Gary Thomas wrote:

> Can you see if these patches fix [at least] the sockbuf corruption
> problem you were seeing?

After some additional testing, it seems the problem is still
there.  It looks like there are routines that access sb structs
without calling sblock/sbunlock.

The ones we've found are in code called by the network task:
tcp_input, tcp_output, etc.  There are calls to sbappend and
similar functions/macros that result in unprotected accesses to
sb struct fields.

My original e-mail pointing out the unreliability of sblock and
sbunlock didn't identify the entire problem.

> The basic idea I've incorporated is to use the eCos scheduler
> lock to emulate the user/kernel behaviour from the BSD world
> (i.e. kernel code cannot be preempted)

I think that sblock and sbunlock should work now, but I don't
think they're called in enough places.

Grant Edwards

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