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Subject[PATCH 1/2] module: encapsulate percpu handling better and record percpu_size
Better encapsulate module static percpu area handling so that code
outsidef of CONFIG_SMP ifdef doesn't deal with mod->percpu directly
and add mod->percpu_size and record percpu_size in it. Both percpu
fields are compiled out on UP. While at it, mark mod->percpu w/
__percpu.

This is to prepare for is_module_percpu_address().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
---
Rusty, can you please ack this? Tested on both SMP and UP.

Thanks.

include/linux/module.h | 5 ++-
kernel/module.c | 66 +++++++++++++++++++++++++------------------------
2 files changed, 39 insertions(+), 32 deletions(-)

Index: work/kernel/module.c
===================================================================
--- work.orig/kernel/module.c
+++ work/kernel/module.c
@@ -370,27 +370,33 @@ EXPORT_SYMBOL_GPL(find_module);

#ifdef CONFIG_SMP

-static void *percpu_modalloc(unsigned long size, unsigned long align,
- const char *name)
+static inline void __percpu *mod_percpu(struct module *mod)
{
- void *ptr;
+ return mod->percpu;
+}

+static int percpu_modalloc(struct module *mod,
+ unsigned long size, unsigned long align)
+{
if (align > PAGE_SIZE) {
printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
- name, align, PAGE_SIZE);
+ mod->name, align, PAGE_SIZE);
align = PAGE_SIZE;
}

- ptr = __alloc_reserved_percpu(size, align);
- if (!ptr)
+ mod->percpu = __alloc_reserved_percpu(size, align);
+ if (!mod->percpu) {
printk(KERN_WARNING
"Could not allocate %lu bytes percpu data\n", size);
- return ptr;
+ return -ENOMEM;
+ }
+ mod->percpu_size = size;
+ return 0;
}

-static void percpu_modfree(void *freeme)
+static void percpu_modfree(struct module *mod)
{
- free_percpu(freeme);
+ free_percpu(mod->percpu);
}

static unsigned int find_pcpusec(Elf_Ehdr *hdr,
@@ -400,24 +406,28 @@ static unsigned int find_pcpusec(Elf_Ehd
return find_sec(hdr, sechdrs, secstrings, ".data.percpu");
}

-static void percpu_modcopy(void *pcpudest, const void *from, unsigned long size)
+static void percpu_modcopy(struct module *mod,
+ const void *from, unsigned long size)
{
int cpu;

for_each_possible_cpu(cpu)
- memcpy(pcpudest + per_cpu_offset(cpu), from, size);
+ memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
}

#else /* ... !CONFIG_SMP */

-static inline void *percpu_modalloc(unsigned long size, unsigned long align,
- const char *name)
+static inline void __percpu *mod_percpu(struct module *mod)
{
return NULL;
}
-static inline void percpu_modfree(void *pcpuptr)
+static inline int percpu_modalloc(struct module *mod,
+ unsigned long size, unsigned long align)
+{
+ return -ENOMEM;
+}
+static inline void percpu_modfree(struct module *mod)
{
- BUG();
}
static inline unsigned int find_pcpusec(Elf_Ehdr *hdr,
Elf_Shdr *sechdrs,
@@ -425,8 +435,8 @@ static inline unsigned int find_pcpusec(
{
return 0;
}
-static inline void percpu_modcopy(void *pcpudst, const void *src,
- unsigned long size)
+static inline void percpu_modcopy(struct module *mod,
+ const void *from, unsigned long size)
{
/* pcpusec should be 0, and size of that section should be 0. */
BUG_ON(size != 0);
@@ -1400,8 +1410,7 @@ static void free_module(struct module *m
/* This may be NULL, but that's OK */
module_free(mod, mod->module_init);
kfree(mod->args);
- if (mod->percpu)
- percpu_modfree(mod->percpu);
+ percpu_modfree(mod);
#if defined(CONFIG_MODULE_UNLOAD)
if (mod->refptr)
free_percpu(mod->refptr);
@@ -1520,7 +1529,7 @@ static int simplify_symbols(Elf_Shdr *se
default:
/* Divert to percpu allocation if a percpu var. */
if (sym[i].st_shndx == pcpuindex)
- secbase = (unsigned long)mod->percpu;
+ secbase = (unsigned long)mod_percpu(mod);
else
secbase = sechdrs[sym[i].st_shndx].sh_addr;
sym[i].st_value += secbase;
@@ -1954,7 +1963,7 @@ static noinline struct module *load_modu
unsigned int modindex, versindex, infoindex, pcpuindex;
struct module *mod;
long err = 0;
- void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
+ void *ptr = NULL; /* Stops spurious gcc warning */
unsigned long symoffs, stroffs, *strmap;

mm_segment_t old_fs;
@@ -2094,15 +2103,11 @@ static noinline struct module *load_modu

if (pcpuindex) {
/* We have a special allocation for this section. */
- percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size,
- sechdrs[pcpuindex].sh_addralign,
- mod->name);
- if (!percpu) {
- err = -ENOMEM;
+ err = percpu_modalloc(mod, sechdrs[pcpuindex].sh_size,
+ sechdrs[pcpuindex].sh_addralign);
+ if (err)
goto free_mod;
- }
sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
- mod->percpu = percpu;
}

/* Determine total sizes, and put offsets in sh_entsize. For now
@@ -2317,7 +2322,7 @@ static noinline struct module *load_modu
sort_extable(mod->extable, mod->extable + mod->num_exentries);

/* Finally, copy percpu area over. */
- percpu_modcopy(mod->percpu, (void *)sechdrs[pcpuindex].sh_addr,
+ percpu_modcopy(mod, (void *)sechdrs[pcpuindex].sh_addr,
sechdrs[pcpuindex].sh_size);

add_kallsyms(mod, sechdrs, hdr->e_shnum, symindex, strindex,
@@ -2409,8 +2414,7 @@ static noinline struct module *load_modu
module_free(mod, mod->module_core);
/* mod will be freed with core. Don't access it beyond this line! */
free_percpu:
- if (percpu)
- percpu_modfree(percpu);
+ percpu_modfree(mod);
free_mod:
kfree(args);
kfree(strmap);
Index: work/include/linux/module.h
===================================================================
--- work.orig/include/linux/module.h
+++ work/include/linux/module.h
@@ -329,8 +329,11 @@ struct module
struct module_notes_attrs *notes_attrs;
#endif

+#ifdef CONFIG_SMP
/* Per-cpu data. */
- void *percpu;
+ void __percpu *percpu;
+ unsigned int percpu_size;
+#endif

/* The command line arguments (may be mangled). People like
keeping pointers to this stuff */

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