In order to support synchronization in a process with a single
gralloc handle we require the ability to write lock a buffer
while it is already read locked by the same handle. This change
extends the concept of an exclusive write lock or recursive read
locks to a genlock handle (rather than the genlock lock).
Genlock cannot provide deadlock protection because the same
handle can be used simultaneously by a producer and consumer.
In practice an error will still be generated when the timeout
expires.
CRs-fixed: 356263
Change-Id: I322e7fadc8b43287f53b211242b176d3de731db2
Signed-off-by: Jeff Boody <jboody@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Allowing a lock to be asynchronously released while a handle
was still active turned out to be too dangerous to use in a
multi-threaded environment and it served no pratical
purpose anyway. Handles now hold an attached lock until they
are destroyed.
CRs-fixed: 333141
Change-Id: Ic0dedbad8050ff01927ddb165c65a939bf297c10
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Add a generic locking API for situations where multiple user-space
processes and/or kernel drivers need to cooordinate access to a
shared resource such as a graphics buffer.
Change-Id: Ic0dedbad74b970d7bd1a6624a845b5b1b9847443
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
