am53c974: Fix crash during modprobe

On systems with shared interrupts the interrupt routine might
be called as soon as the interrupt is enabled.
As this might happen before pci_set_drvdata() is called the
system would crash.
Reported-by: Andreas Brogle <anbro@ok.de>
Tested-by: Andreas Brogle <anbro@ok.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

drivers/scsi/am53c974.c

@@ -476,6 +476,8 @@ static int pci_esp_probe_one(struct pci_dev *pdev,
 		goto fail_unmap_regs;
 	}
 
+	pci_set_drvdata(pdev, pep);
+
 	err = request_irq(pdev->irq, scsi_esp_intr, IRQF_SHARED,
 			  DRV_MODULE_NAME, esp);
 	if (err < 0) {
@@ -496,8 +498,6 @@ static int pci_esp_probe_one(struct pci_dev *pdev,
 	/* Assume 40MHz clock */
 	esp->cfreq = 40000000;
 
-	pci_set_drvdata(pdev, pep);
-
 	err = scsi_esp_register(esp, &pdev->dev);
 	if (err)
 		goto fail_free_irq;
@@ -507,6 +507,7 @@ static int pci_esp_probe_one(struct pci_dev *pdev,
 fail_free_irq:
 	free_irq(pdev->irq, esp);
 fail_unmap_command_block:
+	pci_set_drvdata(pdev, NULL);
 	pci_free_consistent(pdev, 16, esp->command_block,
 			    esp->command_block_dma);
 fail_unmap_regs:
@@ -530,6 +531,7 @@ static void pci_esp_remove_one(struct pci_dev *pdev)
 
 	scsi_esp_unregister(esp);
 	free_irq(pdev->irq, esp);
+	pci_set_drvdata(pdev, NULL);
 	pci_free_consistent(pdev, 16, esp->command_block,
 			    esp->command_block_dma);
 	pci_iounmap(pdev, esp->regs);