CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2017/02/08 09:08:06
Modified files:
sys/dev/pv : xen.c
Log message:
Fixup incorrect test when allocating grant table entries
An xnf & xbf attach/detach loop has revealed that sometimes when we're
about to free a grant table entry that is still in use which is a grave
mistake code wise. Turned out we could allocate an entry twice because
of an incorrect test that took flags value into account when making the
decision regarding availability of a given entry. At the same time,
upon releasing the entry we explicitly CAS in 0 into the flags making
this check bogus.
While here be explicit about starting flags by initializing them to 0
and always panic when the "double free" condition is encountered.
rzalamena@ has lent me his eyes and has double-checked the condition.
