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scsi: always increment reference count

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James reported:
> After e513cc1 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: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2015-01-23 13:22:47 +10:30
parent d5db139ab3
commit dc4515ea26
1 changed files with 3 additions and 10 deletions
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13
drivers/scsi/scsi.c
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@ -986,9 +986,9 @@ int scsi_device_get(struct scsi_device *sdev)
return -ENXIO; return -ENXIO;
if (!get_device(&sdev->sdev_gendev)) if (!get_device(&sdev->sdev_gendev))
return -ENXIO; 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) */ * from module exit (like cache flush) */
try_module_get(sdev->host->hostt->module); __module_get(sdev->host->hostt->module);
return 0; return 0;
} }
@ -1004,14 +1004,7 @@ EXPORT_SYMBOL(scsi_device_get);
*/ */
void scsi_device_put(struct scsi_device *sdev) void scsi_device_put(struct scsi_device *sdev)
{ {
#ifdef CONFIG_MODULE_UNLOAD module_put(sdev->host->hostt->module);
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
put_device(&sdev->sdev_gendev); put_device(&sdev->sdev_gendev);
} }
EXPORT_SYMBOL(scsi_device_put); EXPORT_SYMBOL(scsi_device_put);