ion: replace userspace handle cookies with idr

Userspace handles should not leak kernel virtual addresses to
userspace.  They have to be validated by looking them up in an
rbtree anyways, so replace them with an idr and validate them
by using idr_find to convert the id number to the struct
ion_handle pointer.

Change-Id: Iab5667ba6f3a73256fec3949b23a9a6f8e14a283
Signed-off-by: Colin Cross <ccross@android.com>
Git-commit: 1126d98d8e34d771afcc72ce5d1c37ad4d474402
Git-repo: https://android.googlesource.com/kernel/common
[mitchelh@codeaurora.org: conflicts due to msm changes]
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
ion: don't use id 0 for handle cookie

ion userspace clients think that the cookie is a pointer, so they
use NULL to check if the handle has been initialized.  Set the first
id number to 1.

Change-Id: Ifb9af6029a8b08f57e41bc6160cc11e11001a2a9
Signed-off-by: Colin Cross <ccross@android.com>
Git-commit: 66df93b4c9e78cf433b76d7fe3da4cc7fd06c36b
Git-repo: https://android.googlesource.com/kernel/common
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
ion: add new ion_user_handle_t type for the user-space token

Declare new ion_user_handle_t type to contain the token returned to user-space.
This allows a 2-step migration of the user-space code to a new kernel header
first, then will allow us to change the definition of the ion_user_handle_type_t
to int without breaking the API.

Change-Id: I4200b6600df8e56fe98cf1580a13a65cb25ec646
Signed-off-by: Rom Lemarchand <romlem@google.com>
(cherry picked from commit ebb8269bbb05b06ecedca3e21b3e65f23d48eadd)
Git-commit: 29f271de6ffdf6a96375cd244986617e87afc8d0
Git-repo: https://android.googlesource.com/kernel/common
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
ion: hold reference to handle after ion_uhandle_get

commit 1262ab1846cf76f7549c66ef709120dbfbe6d49f (ion: replace
userspace handle cookies with idr) broke the locking in ion.
The ION_IOC_FREE and ION_IOC_MAP ioctls were relying on
ion_handle_validate to detect the case where a call raced
with another ION_IOC_FREE which may have freed the struct
ion_handle.

Rename ion_uhandle_get to ion_handle_get_by_id, and have it
take the client lock and return with an extra reference to
the handle.  Make each caller put its reference once it
is done with the handle.

Also modify users of ion_handle_validate to continue to hold
the client lock after calling ion_handle_validate until
they are done with the handle, and warn if ion_handle_validate
is called without the client lock held.

Change-Id: I56da5624fca3bed4ee24806b6ec39de903543341
Signed-off-by: Colin Cross <ccross@android.com>
Git-commit: 33a57aa073dac709bcdcba23bc4e2e7fcc6330f6
Git-repo: https://android.googlesource.com/kernel/common
[mitchelh@codeaurora.org: minor merge conflicts due to some missing
 casts since we haven't brought in the change that makes
 ion_user_handle_t an int.]
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
ion: export a few handle-related APIs

There are a few APIs (ion_handle_put and ion_handle_get_by_id) that are
useful for implementing Ion extensions (e.g. custom ioctl
handlers). Remove the `static' to make these APIs available to other Ion
code.

Change-Id: Ice8767853f628d8178e96a36db3da02fa97f3235
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>