[Xen-devel] [xen-devel] create irq failed due to move_cleanup_count always being set

[Liuyongan <liuyongan@xxxxxxxxxx>]

Hi, all
   
    I'm using xen-4.0 to do a test. And when I create a domain, it failed due 
to create_irq() failure. As only 33 domains were successfully created and 
destroyed before I got the continuous failures, and the domain just before the 
failure was properly destroyed(at least destroy_irq() was properly called, 
which will clear move_in_progress, according to the prink-message). So I can 
conclude for certain that __assign_irq_vector failed due to move_cleanup_count 
always being set. 

//this is the normal case when create and destroy domain whose id is 31;
(XEN) irq.c:1232:d0 bind pirq 79, irq 77, share flag:0
(XEN) irq.c:1377: dom31: pirq 79, irq 77 force unbind
(XEN) irq.c:1593: dom31: forcing unbind of pirq 79
(XEN) irq.c:223, destroy irq 77

//domain id 32 is created and destroyed correctly also.
(XEN) irq.c:1232:d0 bind pirq 79, irq 77, share flag:0
(XEN) irq.c:1377: dom32: pirq 79, irq 77 force unbind
(XEN) irq.c:1593: dom32: forcing unbind of pirq 79
(XEN) irq.c:223, destroy irq 77

//all the subsequent domain creation failed, below lists only 3 times:
(XEN) physdev.c:88: dom33: can't create irq for msi!
(XEN) physdev.c:88: dom34: can't create irq for msi!
(XEN) physdev.c:88: dom35: can't create irq for msi!

     I think this might be a bug and might have fixed, so I compare my code 
with 4.1.2 and search the mail list for potential patches. 
(http://xen.markmail.org/search/?q=move_cleanup_count#query:move_cleanup_count+page:6+mid:fpkrafqbeyiauvhs+state:results)
 submit a patch which add locks in __assign_irq_vector. Can anybody explain why 
this lock is needed? Or is there a patch that might fix my bug? Thx.

    Addition message: my board is arch-x86, no domains left when failed to 
create new ones, create_irq failure lasted one day until I reboot the board, 
and the irq number allocated is used certainly for a msi dev.

Yong an Liu
2012.1.4

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