From: Vineet Gupta <vgupta@synopsys.com>
Date: Fri, 18 Jan 2013 09:42:19 +0000 (+0530)
Subject: ARC: [Review] Prevent incorrect syscall restarts
X-Git-Tag: v3.9-rc1~25^2~60
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=55bb9480f9159b229ac3c3454c97b62d1e0a7e80;p=pandora-kernel.git

ARC: [Review] Prevent incorrect syscall restarts

Per Al Viro's "signals for dummies" https://lkml.org/lkml/2012/12/6/366
there are 3 golden rules for (not) restarting syscalls:

"	What we need to guarantee is
* restarts do not happen on signals caught in interrupts or exceptions
* restarts do not happen on signals caught in sigreturn()
* restart should happen only once, even if we get through do_signal()
  many times."

ARC Port already handled #1, this patch fixes #2 and #3.

We use the additional state in pt_regs->orig_r8 to ckh if restarting
has already been done once.

Thanks to Al Viro for spotting this.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
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