From 554b0004d0ec4fbd11e08668dfc400f211e8d5c5 Mon Sep 17 00:00:00 2001 From: Kevin Hilman Date: Mon, 16 Sep 2013 15:28:21 -0700 Subject: vtime: Add HAVE_VIRT_CPU_ACCOUNTING_GEN Kconfig With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. In order to use that feature, arch code should be audited to ensure there are no races in concurrent read/write of cputime_t. For example, reading/writing 64-bit cputime_t on some 32-bit arches may require multiple accesses for low and high value parts, so proper locking is needed to protect against concurrent accesses. Therefore, add CONFIG_HAVE_VIRT_CPU_ACCOUNTING_GEN which arches can enable after they've been audited for potential races. This option is automatically enabled on 64-bit platforms. Feature requested by Frederic Weisbecker. Signed-off-by: Kevin Hilman Cc: Ingo Molnar Cc: Russell King Cc: Paul E. McKenney Cc: Arm Linux Signed-off-by: Frederic Weisbecker --- kernel/time/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/time') diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 2b62fe8..f148475 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -101,6 +101,7 @@ config NO_HZ_FULL depends on HAVE_CONTEXT_TRACKING # VIRT_CPU_ACCOUNTING_GEN dependency depends on 64BIT + depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON select RCU_USER_QS select RCU_NOCB_CPU -- cgit v1.1 From ff3fb2541246a83ce56c61d14df30b7a22e4302b Mon Sep 17 00:00:00 2001 From: Kevin Hilman Date: Mon, 16 Sep 2013 15:28:19 -0700 Subject: nohz: Drop generic vtime obsolete dependency on CONFIG_64BIT The CONFIG_64BIT requirement on vtime can finally be removed since we now depend on HAVE_VIRT_CPU_ACCOUNTING_GEN which already takes care of the arch ability to handle nsecs based cputime_t safely. Signed-off-by: Kevin Hilman Cc: Ingo Molnar Cc: Russell King Cc: Paul E. McKenney Cc: Arm Linux Signed-off-by: Frederic Weisbecker --- kernel/time/Kconfig | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/time') diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index f148475..3ce6e8c 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -100,7 +100,6 @@ config NO_HZ_FULL # RCU_USER_QS dependency depends on HAVE_CONTEXT_TRACKING # VIRT_CPU_ACCOUNTING_GEN dependency - depends on 64BIT depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON select RCU_USER_QS -- cgit v1.1