Re: acpi_memhotplug.c: don't allow to eject the memory device if it is being used

[Dan Carpenter <dan.carpenter@oracle.com>]

On Tue, Nov 06, 2012 at 10:10:11AM +0800, Wen Congyang wrote:
> At 11/06/2012 02:11 AM, Dan Carpenter Wrote:
> > Hello Wen Congyang,
> > 
> > The patch 306859f13dc1: "acpi_memhotplug.c: don't allow to eject the
> > memory device if it is being used" from Nov 3, 2012, leads to the
> > following Smatch warning:
> > drivers/acpi/acpi_memhotplug.c:367 acpi_memory_remove_memory()
> > 	 warn: inconsistent returns mutex:&mem_device->list_lock:
> > 	locked (357,361) unlocked (367)
> 
> Thanks for pointing it out.
> 
> The patch 306859f13dc1 is in akpm's tree, and it conflicts with another
> patch in linux-pm's tree. So Andrew Morton drops them.
> 
> I will resend them based on linux-pm's next tree.

Ok. Today's linux-next version 85fcb3758c10e "ACPI / memory-hotplug:
introduce a mutex lock to protect the list in acpi_memory_device"
has a similar problem and should be fixed as well.

   319  static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
   320  {
   321          int result;
   322          struct acpi_memory_info *info, *n;
   323  
   324          mutex_lock(&mem_device->list_lock);
   325          list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
   326                  if (info->enabled) {
   327                          result = remove_memory(info->start_addr, info->length);
   328                          if (result)
   329                                  return result;
                                        ^^^^^^^^^^^^^
We are still holding the lock here.

   330                  }
   331  
   332                  list_del(&info->list);
   333                  kfree(info);
   334          }
   335          mutex_unlock(&mem_device->list_lock);
   336  
   337          return 0;
   338  }

regards,
dan carpenter