percpu: generalize first chunk allocator selection

Now that all first chunk allocators are in mm/percpu.c, it makes sense
to make generalize percpu_alloc kernel parameter.  Define PCPU_FC_*
and set pcpu_chosen_fc using early_param() in mm/percpu.c.  Arch code
can use the set value to determine which first chunk allocator to use.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 6 insertions, 18 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 1e17711c29d6..b961d99e6416 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -267,16 +267,6 @@ static ssize_t __init setup_pcpu_page(size_t static_size)
                                      pcpup_populate_pte);
 }
 
-/* for explicit first chunk allocator selection */
-static char pcpu_chosen_alloc[16] __initdata;
-
-static int __init percpu_alloc_setup(char *str)
-{
-        strncpy(pcpu_chosen_alloc, str, sizeof(pcpu_chosen_alloc) - 1);
-        return 0;
-}
-early_param("percpu_alloc", percpu_alloc_setup);
-
 static inline void setup_percpu_segment(int cpu)
 {
 #ifdef CONFIG_X86_32
@@ -307,19 +297,17 @@ void __init setup_per_cpu_areas(void)
          * each allocator for details.
          */
         ret = -EINVAL;
-        if (strlen(pcpu_chosen_alloc)) {
-                if (strcmp(pcpu_chosen_alloc, "page")) {
-                        if (!strcmp(pcpu_chosen_alloc, "lpage"))
+        if (pcpu_chosen_fc != PCPU_FC_AUTO) {
+                if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+                        if (pcpu_chosen_fc == PCPU_FC_LPAGE)
                                 ret = setup_pcpu_lpage(static_size, true);
-                        else if (!strcmp(pcpu_chosen_alloc, "embed"))
-                                ret = setup_pcpu_embed(static_size, true);
                         else
-                                pr_warning("PERCPU: unknown allocator %s "
-                                           "specified\n", pcpu_chosen_alloc);
+                                ret = setup_pcpu_embed(static_size, true);
+
                         if (ret < 0)
                                 pr_warning("PERCPU: %s allocator failed (%zd), "
                                            "falling back to page size\n",
-                                           pcpu_chosen_alloc, ret);
+                                           pcpu_fc_names[pcpu_chosen_fc], ret);
                 }
         } else {
                 ret = setup_pcpu_lpage(static_size, false);