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Commit dc4515ea authored by Rusty Russell's avatar Rusty Russell
Browse files

scsi: always increment reference count 



James reported:
> After e513cc1c module: Remove stop_machine from module unloading,
> module_refcount() is returning (unsigned long)-1 when called from within
> a routine that runs in module_exit.  This is confusing the scsi device
> put code which is coded to detect a module_refcount() of zero for
> running within a module exit routine and not try to do another
> module_put.  The fix is to restore the original behaviour of
> module_refcount() and return zero if we're running inside an exit
> routine.

The correct fix is to turn try_module_get() into __module_get(), and
always do the module_put().

Acked-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent d5db139a

drivers/scsi/scsi.c

+3 −10
Original line number Diff line number Diff line
@@ -986,9 +986,9 @@ int scsi_device_get(struct scsi_device *sdev) 
		return -ENXIO;

	if (!get_device(&sdev->sdev_gendev))

		return -ENXIO;

	/* We can fail this if we're doing SCSI operations

	/* We can fail try_module_get if we're doing SCSI operations

	 * from module exit (like cache flush) */

	try_module_get(sdev->host->hostt->module);

	__module_get(sdev->host->hostt->module);



	return 0;

}
@@ -1004,14 +1004,7 @@ EXPORT_SYMBOL(scsi_device_get); 
 */

void scsi_device_put(struct scsi_device *sdev)

{

#ifdef CONFIG_MODULE_UNLOAD

	struct module *module = sdev->host->hostt->module;



	/* The module refcount will be zero if scsi_device_get()

	 * was called from a module removal routine */

	if (module && module_refcount(module) != 0)

		module_put(module);

#endif

	module_put(sdev->host->hostt->module);

	put_device(&sdev->sdev_gendev);

}

EXPORT_SYMBOL(scsi_device_put);