random: vDSO: Remove ifdeffery

Recent cleanups of the vDSO headers allow the unconditional inclusion of
vdso/datapage.h and the declarations it provides. This also means that
the declaration of vdso_k_rng_data is always visible and its usage does
not need to be guarded by ifdefs anymore. Instead use IS_ENABLED().

Signed-off-by: Thomas Weißschuh <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Borislav Petkov (AMD) <[e-mail]>
Reviewed-by: Jason A. Donenfeld <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/char/random.c

···
 #include <linux/sched/isolation.h>
 #include <crypto/chacha.h>
 #include <crypto/blake2s.h>
-#ifdef CONFIG_VDSO_GETRANDOM
 #include <vdso/datapage.h>
-#endif
 #include <asm/archrandom.h>
 #include <asm/processor.h>
 #include <asm/irq.h>
···
 	if (next_gen == ULONG_MAX)
 		++next_gen;
 	WRITE_ONCE(base_crng.generation, next_gen);
-#ifdef CONFIG_VDSO_GETRANDOM
+
 	/* base_crng.generation's invalid value is ULONG_MAX, while
 	 * vdso_k_rng_data->generation's invalid value is 0, so add one to the
 	 * former to arrive at the latter. Use smp_store_release so that this
···
 	 * because the vDSO side only checks whether the value changed, without
 	 * actually using or interpreting the value.
 	 */
-	smp_store_release((unsigned long *)&vdso_k_rng_data->generation, next_gen + 1);
-#endif
+	if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+		smp_store_release((unsigned long *)&vdso_k_rng_data->generation, next_gen + 1);
+
 	if (!static_branch_likely(&crng_is_ready))
 		crng_init = CRNG_READY;
 	spin_unlock_irqrestore(&base_crng.lock, flags);
···
 		if (system_dfl_wq)
 			queue_work(system_dfl_wq, &set_ready);
 		atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
-#ifdef CONFIG_VDSO_GETRANDOM
-		WRITE_ONCE(vdso_k_rng_data->is_ready, true);
-#endif
+		if (IS_ENABLED(CONFIG_VDSO_GETRANDOM))
+			WRITE_ONCE(vdso_k_rng_data->is_ready, true);
 		wake_up_interruptible(&crng_init_wait);
 		kill_fasync(&fasync, SIGIO, POLL_IN);
 		pr_notice("crng init done\n");