[Xen-devel] Why cast to "signed short" before checking the return value of gnttab_claim_grant_reference() in xen-netfront.c?

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

Hi,

Would anyone please help with a question on xen-netfront.c code?

In xen-netfront.c, the return value of gnttab_claim_grant_reference() is
checked with "BUG_ON((signed short)ref < 0);". Why we use signed short here
while the return value is of uint32_t? 

Am I missing anything or can I send a patch to fix this issue? In
xen-blkfront.c and xen-scsifront.c "BUG_ON(gnt_list_entry->gref == -ENOSPC);"
is involved to check return value. 

The guest kernel would panic after grant refs reach a very large number (when
guest is attached with large number of devices and live migrated).

Thank you very much!

Dongli Zhang

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