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| author |   Frederic Weisbecker <frederic@kernel.org> | 2020-01-27 16:41:52 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <frederic@kernel.org> | 2020-02-14 16:05:04 +0100 |
| commit | 490f561b783dac2c4825e288e6dbbf83481eea34 (patch) | |
| tree | 9d51328accd11ec6eafd8e1cc0e0a150c451b764 /kernel/context_tracking.c | |
| parent | x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY (diff) | |
| download | linux-dev-490f561b783dac2c4825e288e6dbbf83481eea34.tar.xz linux-dev-490f561b783dac2c4825e288e6dbbf83481eea34.zip | |
context-tracking: Introduce CONFIG_HAVE_TIF_NOHZ
A few archs (x86, arm, arm64) don't rely anymore on TIF_NOHZ to call
into context tracking on user entry/exit but instead use static keys
(or not) to optimize those calls. Ideally every arch should migrate to
that behaviour in the long run.
Settle a config option to let those archs remove their TIF_NOHZ
definitions.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/context_tracking.c')
| -rw-r--r-- | kernel/context_tracking.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 0296b4bda8f1..ce430885c26c 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -198,11 +198,13 @@ void __init context_tracking_cpu_set(int cpu) if (initialized) return; +#ifdef CONFIG_HAVE_TIF_NOHZ /* * Set TIF_NOHZ to init/0 and let it propagate to all tasks through fork * This assumes that init is the only task at this early boot stage. */ set_tsk_thread_flag(&init_task, TIF_NOHZ); +#endif WARN_ON_ONCE(!tasklist_empty()); initialized = true; |