[SCSI] sym53c8xx: fixes two bugs related to chip reset

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@w.pl>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index 09bbb39..dc9af8f 100644 (file)
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -609,22 +609,24 @@ static int sym_eh_handler(int op, char *opname, struct scsi_cmnd *cmd)
         */
 #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);
+               spin_lock_irq(shost->host_lock);
+               sym_data->io_reset = NULL;
+               spin_unlock_irq(shost->host_lock);
                if (!finished_reset)
                        return SCSI_FAILED;
        }
@@ -1879,7 +1881,6 @@ static void sym2_io_resume(struct pci_dev *pdev)
        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);
 }