This is so that the system process can capture kernel thread stacks when the
watchdog detects a deadlock. Previously, /proc/kmsg was root/root and mode
0400, and /proc/sysrq-trigger was root/root and mode 0200. With this
change, /proc/kmsg becomes root/system and 0440, and /proc/sysrq-trigger
becomes root/system and 0220.
Change-Id: Iac46bd10bd11d495024afeb5d693107ce5074791
Re-use the file descriptor to change the cgroups. There's a fast path
in the kernel for the case where the value's already uncahnged. Also,
this is okay because the kernel ignores the write offset. This is
essentially a ioctl-ish/datagram interface, despite being a fd we're
writing to.
This reduces Dalvik->Dalvik void/void Binder calls on Sapphire from
~1.2 to ~0.8 ms. This is a bit slower than the ~0.7 ms we get
avoiding the write altogether.
strace confirms:
[pid 1557] ioctl(21, 0xc0186201 <unfinished ...>
[pid 1556] <... ioctl resumed> , 0x45399cd0) = 0
[pid 1556] write(22, "1556", 4) = 4
[pid 1556] ioctl(21, 0xc0186201 <unfinished ...>
[pid 1555] <... ioctl resumed> , 0x45299cd0) = 0
[pid 1555] write(22, "1555", 4) = 4
[pid 1555] ioctl(21, 0xc0186201 <unfinished ...>
[pid 1554] <... ioctl resumed> , 0x45199cd0) = 0
[pid 1554] write(22, "1554", 4) = 4
BUG=2660235
Change-Id: Ia9f9e1d5b792eaebc9560f89931faf6df0cf9c0d
- use static /dev/cpuctl filenames, rather than sprintf() on the fly
- use a custom formatter instead of sprintf() for the tid number
This is a simplified version of Dan's original
Ifc9c81f74fe65f0695ead53b30194bc6adf00da0 to be less risky for Froyo.
Bug: 2660235
Change-Id: I744bbc2ec01fd2569612c814a497df40a933b622
Typical usage is 'run-as <package-name> <command>' to run <command>
in the data directory, and the user id, of <package-name> if, and only
if <package-name> is the name of an installed and debuggable application.
This relies on the /data/system/packages.list file generated by the
PackageManager service.
BEWARE: This is intended to be available on production devices !
On devices that use a pppd for cellular network access, a pppd-ril
process needs to run as root to configure the connection. Changing
the process to suid-root in the build image is the only known way
to avoid needing to remount the system image at boot to accomplish
the same thing.
Change-Id: I6c778391b8040ee818343e304891e7d341cc729b
This helps us recover when things go wrong during automated testing.
Change-Id: I006dbfaff7f70d51398ff12fbddcaee751453b78
Signed-off-by: Mike Lockwood <lockwood@android.com>
This reverts commit a7d88224ff.
This cgroup subsys should be mounted on it's own mount-point, since it's
addition to /dev/cpuctl causes the cpu subsys to EPERM
Nick Kralevich