RE: Problem of concurrency in arch/ppc/8260_io/uart.c

Hi,

Hi Steffen.

I have seen a similar problem for the 2.4.20.

When I force a lot of console output via the following command:

   while true; do cd /; ls -R; done

and type-in some letters in parallel, the console
becomes crazy.

My custom mpc860 also becomes crazy or just locks up when I do this. The
drivers are pretty the same, so this is no surprise.

I have added some instrumentation in order to dump the
TX Buffer Descriptor Table. I have found that the
hardware pointer (TBPTR) and the software pointer (tx_cur)
are not more synchronized together:
Inside uart.c, there are the following output routines:

[SNIP]

   rs_8xx_put_char()
   rs_8xx_write()
   rs_8xx_send_xchar()
   my_console_write()

I think there must be a synchronization accessing the
TX BD table. I suggest the patch attached.

Hmm, don't you turn off irq's for a long time with this patch?

 Jocke

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