From d45ad06273f797f6239b97fd9962ecd81eec847f Mon Sep 17 00:00:00 2001 From: Haavard Skinnemoen Date: Fri, 15 Feb 2008 14:38:40 +0100 Subject: avr32: Call tick_nohz_{stop,restart}_sched_tick() in idle loop This fixes a hang on boot with nohz enabled. nohz is not actually supported in mainline yet, but patches that add support for it are currently under review. When nohz is compiled out, the functions are no-ops, so this patch results in no functional change, but it arguably makes the code more correct. Signed-off-by: Haavard Skinnemoen --- arch/avr32/kernel/process.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/avr32/kernel') diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c index eaaa69b..faf8d0e 100644 --- a/arch/avr32/kernel/process.c +++ b/arch/avr32/kernel/process.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -30,8 +31,10 @@ void cpu_idle(void) { /* endless idle loop with no priority at all */ while (1) { + tick_nohz_stop_sched_tick(); while (!need_resched()) cpu_idle_sleep(); + tick_nohz_restart_sched_tick(); preempt_enable_no_resched(); schedule(); preempt_disable(); -- cgit v1.1 From 325d6f5593b40b5a48cf4ade74c01681f2ff6044 Mon Sep 17 00:00:00 2001 From: Haavard Skinnemoen Date: Wed, 27 Feb 2008 14:04:29 +0100 Subject: avr32: Fix OCD refcounting bug Iff the parent has TIF_DEBUG set, _and_ clone_flags includes CLONE_PTRACE we should set the TIF_DEBUG flag for the child and increment the ocd refcount. Otherwise, the TIF_DEBUG flag must be unset. Currently, the child inherits TIF_DEBUG from the parent before copy_thread is called, so TIF_DEBUG may be already be set before we determine whether the child is supposed to inherit debugging capabilities from the parent or not. This means that ocd_enable() won't increment the refcount, because TIF_DEBUG is already set, and that TIF_DEBUG will be set for processes that aren't being debugged. This leads to a refcounting asymmetry, which may show up as ------------[ cut here ]------------ Badness at arch/avr32/kernel/ocd.c:73 PC is at ocd_disable+0x34/0x60 LR is at put_lock_stats+0xa/0x20 as reported by David Brownell. Happens when strace'ing a process that forks a new child process, e.g. "strace mount -tjffs2 mtd1 /mnt", and subsequently killing the child process (e.g. "umount /mnt".) Signed-off-by: Haavard Skinnemoen --- arch/avr32/kernel/process.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/avr32/kernel') diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c index faf8d0e..7f4af0b 100644 --- a/arch/avr32/kernel/process.c +++ b/arch/avr32/kernel/process.c @@ -348,6 +348,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp, p->thread.cpu_context.ksp = (unsigned long)childregs; p->thread.cpu_context.pc = (unsigned long)ret_from_fork; + clear_tsk_thread_flag(p, TIF_DEBUG); if ((clone_flags & CLONE_PTRACE) && test_thread_flag(TIF_DEBUG)) ocd_enable(p); -- cgit v1.1