Date: Tue, 29 Jun 2004 17:50:07 -0500
From: linas@austin.ibm.com
To: paulus@au1.ibm.com, paulus@samba.org
Cc: linuxppc64-dev@lists.linuxppc.org, linux-kernel@vger.kernel.org
Subject: [PATCH] PPC64: lockfix for rtas error log
Message-ID: <20040629175007.P21634@forte.austin.ibm.com>
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Paul, 

Could you please apply the following path to the ameslab tree, and/or 
forward it to the main 2.6 kernel maintainers.

This patch moves the location of a lock in order to protect
the contents of a buffer until it has been copied to its final
destination. Prior to this, a race existed whereby the buffer
could be filled even while it was being emptied.

Signed-off-by: Linas Vepstas <linas@linas.org>

--linas


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--- arch/ppc64/kernel/rtas.c.orig-pre-lockfix	2004-06-29 17:02:12.000000000 -0500
+++ arch/ppc64/kernel/rtas.c	2004-06-29 17:14:05.000000000 -0500
@@ -134,9 +134,10 @@ log_rtas_error(void)
 
 	spin_lock_irqsave(&rtas.lock, s);
 	rc = __log_rtas_error();
-	spin_unlock_irqrestore(&rtas.lock, s);
-	if (rc == 0)
+	if (rc == 0) {
 		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
+	}
+	spin_unlock_irqrestore(&rtas.lock, s);
 }
 
 int
@@ -193,12 +194,13 @@ rtas_call(int token, int nargs, int nret
 			outputs[i] = rtas_args->rets[i+1];
 	ret = (int)((nret > 0) ? rtas_args->rets[0] : 0);
 
+	if (logit) {
+		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
+	}
+	
 	/* Gotta do something different here, use global lock for now... */
 	spin_unlock_irqrestore(&rtas.lock, s);
 
-	if (logit)
-		log_error(rtas_err_buf, ERR_TYPE_RTAS_LOG, 0);
-
 	return ret;
 }
 

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