Commit 821e02f2 authored Oct 23, 2015 by Andrew Bresticker Committed by Vikram Mulukutla Jul 26, 2016

CHROMIUM: android: binder: Fix potential scheduling-while-atomic



Commit f1e7f0a724f6 ("android: binder: Disable preemption while holding
the global binder lock.") re-enabled preemption around most of the sites
where calls to potentially sleeping functions were made, but missed
__alloc_fd(), which can sleep if the fdtable needs to be resized.
Re-enable preemption around __alloc_fd() as well as __fd_install() which
can now sleep in upstream kernels as of commit 8a81252b ("fs/file.c:
don't acquire files->file_lock in fd_install()").

BUG=chrome-os-partner:44012
TEST=Build and boot on Smaug.

Change-Id: I9819c4b95876f697e75b1b84810b6c520d9c33ec
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/308582


Reviewed-by: Stephen Barber <smbarber@chromium.org>
Reviewed-by: Riley Andrews <riandrews@google.com>
Git-repo: https://source.codeaurora.org/quic/la/kernel/msm-4.4


Git-commit: c267ff1d548ed1bdad6a08f1c70776c5e60d569e
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>

parent e4045d60

drivers/android/binder.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -379,6 +379,7 @@ static int task_get_unused_fd_flags(struct binder_proc *proc, int flags)
		struct files_struct *files = proc->files;
		unsigned long rlim_cur;
		unsigned long irqs;
		int ret;

		if (files == NULL)
		return -ESRCH;
		@@ -389,7 +390,11 @@ static int task_get_unused_fd_flags(struct binder_proc *proc, int flags)
		rlim_cur = task_rlimit(proc->tsk, RLIMIT_NOFILE);
		unlock_task_sighand(proc->tsk, &irqs);

		return __alloc_fd(files, 0, rlim_cur, flags);
		preempt_enable_no_resched();
		ret = __alloc_fd(files, 0, rlim_cur, flags);
		preempt_disable();

		return ret;
		}

		/*
		@@ -398,8 +403,11 @@ static int task_get_unused_fd_flags(struct binder_proc *proc, int flags)
		static void task_fd_install(
		struct binder_proc proc, unsigned int fd, struct file file)
		{
		if (proc->files)
		if (proc->files) {
		preempt_enable_no_resched();
		__fd_install(proc->files, fd, file);
		preempt_disable();
		}
		}

		/*