Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-24 Thread Mark Rutland
On Sat, Jul 20, 2019 at 04:54:58PM +0900, Masami Hiramatsu wrote: > Hi Mark, > > On Fri, 19 Jul 2019 10:59:59 +0100 > Mark Rutland wrote: > > > On Thu, Jul 18, 2019 at 11:31:33PM +0900, Masami Hiramatsu wrote: > > > On Thu, 18 Jul 2019 10:20:23 +0100 > > > Mark Rutland wrote: > > > > > > > On

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-20 Thread Masami Hiramatsu
On Sat, 20 Jul 2019 16:32:32 +0900 Masami Hiramatsu wrote: > Hi James, > > On Fri, 19 Jul 2019 09:42:05 +0100 > James Morse wrote: > > > Hi, > > > > On 7/18/19 3:31 PM, Masami Hiramatsu wrote: > > > On Thu, 18 Jul 2019 10:20:23 +0100 > > > Mark Rutland wrote: > > > > > >> On Wed, Jul 17, 20

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-20 Thread Masami Hiramatsu
Hi Mark, On Fri, 19 Jul 2019 10:59:59 +0100 Mark Rutland wrote: > On Thu, Jul 18, 2019 at 11:31:33PM +0900, Masami Hiramatsu wrote: > > On Thu, 18 Jul 2019 10:20:23 +0100 > > Mark Rutland wrote: > > > > > On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: > > > > On Thu, Jul 18,

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-20 Thread Masami Hiramatsu
Hi James, On Fri, 19 Jul 2019 09:42:05 +0100 James Morse wrote: > Hi, > > On 7/18/19 3:31 PM, Masami Hiramatsu wrote: > > On Thu, 18 Jul 2019 10:20:23 +0100 > > Mark Rutland wrote: > > > >> On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: > >>> On Thu, Jul 18, 2019 at 02:43:5

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-19 Thread Mark Rutland
On Thu, Jul 18, 2019 at 11:31:33PM +0900, Masami Hiramatsu wrote: > On Thu, 18 Jul 2019 10:20:23 +0100 > Mark Rutland wrote: > > > On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: > > > On Thu, Jul 18, 2019 at 02:43:58PM +0900, Masami Hiramatsu wrote: > > > > Remove rcu_read_lock

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-19 Thread James Morse
Hi, On 7/18/19 3:31 PM, Masami Hiramatsu wrote: On Thu, 18 Jul 2019 10:20:23 +0100 Mark Rutland wrote: On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: On Thu, Jul 18, 2019 at 02:43:58PM +0900, Masami Hiramatsu wrote: Remove rcu_read_lock()/rcu_read_unlock() from debug exce

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-18 Thread Masami Hiramatsu
On Thu, 18 Jul 2019 10:20:23 +0100 Mark Rutland wrote: > On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: > > On Thu, Jul 18, 2019 at 02:43:58PM +0900, Masami Hiramatsu wrote: > > > Remove rcu_read_lock()/rcu_read_unlock() from debug exception > > > handlers since the software br

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-18 Thread Mark Rutland
On Wed, Jul 17, 2019 at 11:22:15PM -0700, Paul E. McKenney wrote: > On Thu, Jul 18, 2019 at 02:43:58PM +0900, Masami Hiramatsu wrote: > > Remove rcu_read_lock()/rcu_read_unlock() from debug exception > > handlers since the software breakpoint can be hit on idle task. Why precisely do we need to el

Re: [PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-17 Thread Paul E. McKenney
On Thu, Jul 18, 2019 at 02:43:58PM +0900, Masami Hiramatsu wrote: > Remove rcu_read_lock()/rcu_read_unlock() from debug exception > handlers since the software breakpoint can be hit on idle task. The exception entry and exit use irq_enter() and irq_exit(), in this case, correct? Otherwise RCU wil

[PATCH 3/3] arm64: debug: Remove rcu_read_lock from debug exception

2019-07-17 Thread Masami Hiramatsu
Remove rcu_read_lock()/rcu_read_unlock() from debug exception handlers since the software breakpoint can be hit on idle task. Actually, we don't need it because those handlers run in exception context where the interrupts are disabled. This means those are never preempted. Reported-by: Naresh Kam