Re: [Qemu-devel] [PATCH] sh4-linux-user: fix multi-threading regression.

[Peter Maydell]

2012/3/26 Cédric VINCENT <address@hidden>:
> This reverts commit fd4bab10 "target-sh4: optimize exceptions":

[cc'ing Aurelien as the author of that commit]

> the function cpu_restore_state() isn't expected to be called in user-mode,

Is this really true? host_signal_handler() calls cpu_signal_handler()
calls handle_cpu_signala) calls cpu_restore_state() so hopefully
it's OK to be called in at least *some* situations...

> as a consequence it isn't protected from race conditions.  For
> information, syscalls are exceptions on Linux/SH4.
>
> There were two possible fixes: either "tb_lock" is acquired/released
> around the call to cpu_restore_state() [1] or the commit that
> introduced this regression is reverted [2].

Can you explain a bit further what the race condition is that occurs
here?

NB the whole tb_lock thing is broken anyway.

thanks
-- PMM