sched/vtime: Get rid of generic vtime_task_switch() implementation

The generic vtime_task_switch() implementation gets built only
if __ARCH_HAS_VTIME_TASK_SWITCH is not defined, but requires an
architecture to implement arch_vtime_task_switch() callback at
the same time, which is confusing.

Further, arch_vtime_task_switch() is implemented for 32-bit PowerPC
architecture only and vtime_task_switch() generic variant is rather
superfluous.

Simplify the whole vtime_task_switch() wiring by moving the existing
generic implementation to PowerPC.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2cb6e3caada93623f6d4f78ad938ac6cd0e2fda8.1712760275.git.agordeev@linux.ibm.com

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index df20cf201f74..c0fdc6d94fee 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -354,6 +354,28 @@ void vtime_flush(struct task_struct *tsk)
 	acct->hardirq_time = 0;
 	acct->softirq_time = 0;
 }
+
+/*
+ * Called from the context switch with interrupts disabled, to charge all
+ * accumulated times to the current process, and to prepare accounting on
+ * the next process.
+ */
+void vtime_task_switch(struct task_struct *prev)
+{
+	if (is_idle_task(prev))
+		vtime_account_idle(prev);
+	else
+		vtime_account_kernel(prev);
+
+	vtime_flush(prev);
+
+	if (!IS_ENABLED(CONFIG_PPC64)) {
+		struct cpu_accounting_data *acct = get_accounting(current);
+		struct cpu_accounting_data *acct0 = get_accounting(prev);
+
+		acct->starttime = acct0->starttime;
+	}
+}
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
 void __no_kcsan __delay(unsigned long loops)