ueventd: duplicate /dev/ashmem
We want ashmem to only be used via libcutils API, with long-term goal
being deprecation of ashmem with memfd. To do that we route libcutils to
a new source of ashmem fds. We then phase out uses of /dev/ashmem that
doesn't go through libcutils using SELinux.
In Q, we introduced ashmemd as the source of ashmem fds to libcutils.
However, having a separate process and, consequently, binder hops to
handle /dev/ashmem results in performance/memory overhead.
To address the overhead, replace ashmemd with a duplicate of
/dev/ashmem. Name it /dev/ashmem<boot_id>, where boot_id is a random
number generated on each boot. This way we make sure that developers
don't accidentally depend on /dev/ashmem<boot_id>, as that name can't be
hardcoded.
Bug: 139855428
Test: writing "add"/"remove" to /sys/class/misc/ashmem/uevent correctly
adds/removes /dev/ashmem and /dev/ashmem/boot_id
Change-Id: I36d23116048bfcd99903ba46cc133161835a2cfa
diff --git a/init/devices.h b/init/devices.h
index 442c53f..05d64da 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -130,6 +130,7 @@
void HandleDevice(const std::string& action, const std::string& devpath, bool block, int major,
int minor, const std::vector<std::string>& links) const;
void FixupSysPermissions(const std::string& upath, const std::string& subsystem) const;
+ void HandleAshmemUevent(const Uevent& uevent);
std::vector<Permissions> dev_permissions_;
std::vector<SysfsPermissions> sysfs_permissions_;