[PATCH] sym53_8xx_2: fixes two bugs related to chip reset

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From: Krzysztof Helt <krzysztof.h1@xxxxx>

This patch fixes two bugs pointed by James Bottomley:

 1. the if (!sym_data->io_reset).  That variable is only ever filled
    by a stack based completion.  If we find it non empty it means
    this code has been entered twice and we have a severe problem,
    so that should just become a BUG_ON(!sym_data->io_reset).
 2. sym_data->io_reset should be set to NULL before the routine is
    exited otherwise the PCI recovery code could end up completing
    what will be a bogus pointer into the stack.

Big thanks to James Bottomley for help with the patch.

Signed-off-by: Krzysztof Helt <krzysztof.h1@xxxx>

---
I do not know if I understood correctly all James' tips.

diff -urp linux-ref/drivers/scsi/sym53c8xx_2/sym_glue.c linux-new/drivers/scsi/sym53c8xx_2/sym_glue.c
--- linux-ref/drivers/scsi/sym53c8xx_2/sym_glue.c	2007-12-23 20:39:44.000000000 +0100
+++ linux-new/drivers/scsi/sym53c8xx_2/sym_glue.c	2008-01-09 22:22:30.000000000 +0100
@@ -609,22 +609,22 @@ static int sym_eh_handler(int op, char *
 	 */
 #define WAIT_FOR_PCI_RECOVERY	35
 	if (pci_channel_offline(pdev)) {
-		struct completion *io_reset;
 		int finished_reset = 0;
 		init_completion(&eh_done);
 		spin_lock_irq(shost->host_lock);
 		/* Make sure we didn't race */
 		if (pci_channel_offline(pdev)) {
-			if (!sym_data->io_reset)
-				sym_data->io_reset = &eh_done;
-			io_reset = sym_data->io_reset;
+			BUG_ON(!sym_data->io_reset);
+			sym_data->io_reset = &eh_done;
 		} else {
 			finished_reset = 1;
 		}
 		spin_unlock_irq(shost->host_lock);
 		if (!finished_reset)
-			finished_reset = wait_for_completion_timeout(io_reset,
+			finished_reset = wait_for_completion_timeout
+						(sym_data->io_reset,
 						WAIT_FOR_PCI_RECOVERY*HZ);
+		sym_data->io_reset = NULL;
 		if (!finished_reset)
 			return SCSI_FAILED;
 	}
@@ -1879,7 +1879,6 @@ static void sym2_io_resume(struct pci_de
 	spin_lock_irq(shost->host_lock);
 	if (sym_data->io_reset)
 		complete_all(sym_data->io_reset);
-	sym_data->io_reset = NULL;
 	spin_unlock_irq(shost->host_lock);
 }
 


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