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module: neaten __find_symbol, rename to find_symbol
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__find_symbol() has grown over time: there are now 5 different arrays
of symbols it traverses.  It also shouldn't print out a warning on
some calls (ie. verify_symbol which simply checks for name clashes,
and __symbol_put which checks for bugs).

1) Rename to find_symbol: no need for underscores.
2) Use bool and add "warn" parameter to suppress warnings.
3) Make table-driven rather than open coded.

Signed-off-by: Rusty Russell <[email protected]>
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@rustyrussell
rustyrussell committed May 1, 2008
1 parent ea01e79 commit ad9546c
Showing 1 changed file with 125 additions and 121 deletions.
246 changes: 125 additions & 121 deletions kernel/module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -164,131 +164,140 @@ static const struct kernel_symbol *lookup_symbol(const char *name,
return NULL;
}

static void printk_unused_warning(const char *name)
static bool always_ok(bool gplok, bool warn, const char *name)
{
printk(KERN_WARNING "Symbol %s is marked as UNUSED, "
"however this module is using it.\n", name);
printk(KERN_WARNING "This symbol will go away in the future.\n");
printk(KERN_WARNING "Please evalute if this is the right api to use, "
"and if it really is, submit a report the linux kernel "
"mailinglist together with submitting your code for "
"inclusion.\n");
return true;
}

/* Find a symbol, return value, crc and module which owns it */
static unsigned long __find_symbol(const char *name,
struct module **owner,
const unsigned long **crc,
int gplok)
static bool printk_unused_warning(bool gplok, bool warn, const char *name)
{
struct module *mod;
const struct kernel_symbol *ks;

/* Core kernel first. */
*owner = NULL;
ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
if (ks) {
*crc = symversion(__start___kcrctab, (ks - __start___ksymtab));
return ks->value;
if (warn) {
printk(KERN_WARNING "Symbol %s is marked as UNUSED, "
"however this module is using it.\n", name);
printk(KERN_WARNING
"This symbol will go away in the future.\n");
printk(KERN_WARNING
"Please evalute if this is the right api to use and if "
"it really is, submit a report the linux kernel "
"mailinglist together with submitting your code for "
"inclusion.\n");
}
if (gplok) {
ks = lookup_symbol(name, __start___ksymtab_gpl,
__stop___ksymtab_gpl);
if (ks) {
*crc = symversion(__start___kcrctab_gpl,
(ks - __start___ksymtab_gpl));
return ks->value;
}
}
ks = lookup_symbol(name, __start___ksymtab_gpl_future,
__stop___ksymtab_gpl_future);
if (ks) {
if (!gplok) {
printk(KERN_WARNING "Symbol %s is being used "
"by a non-GPL module, which will not "
"be allowed in the future\n", name);
printk(KERN_WARNING "Please see the file "
"Documentation/feature-removal-schedule.txt "
"in the kernel source tree for more "
"details.\n");
}
*crc = symversion(__start___kcrctab_gpl_future,
(ks - __start___ksymtab_gpl_future));
return ks->value;
return true;
}

static bool gpl_only_unused_warning(bool gplok, bool warn, const char *name)
{
if (!gplok)
return false;
return printk_unused_warning(gplok, warn, name);
}

static bool gpl_only(bool gplok, bool warn, const char *name)
{
return gplok;
}

static bool warn_if_not_gpl(bool gplok, bool warn, const char *name)
{
if (!gplok && warn) {
printk(KERN_WARNING "Symbol %s is being used "
"by a non-GPL module, which will not "
"be allowed in the future\n", name);
printk(KERN_WARNING "Please see the file "
"Documentation/feature-removal-schedule.txt "
"in the kernel source tree for more details.\n");
}
return true;
}

ks = lookup_symbol(name, __start___ksymtab_unused,
__stop___ksymtab_unused);
if (ks) {
printk_unused_warning(name);
*crc = symversion(__start___kcrctab_unused,
(ks - __start___ksymtab_unused));
return ks->value;
struct symsearch {
const struct kernel_symbol *start, *stop;
const unsigned long *crcs;
bool (*check)(bool gplok, bool warn, const char *name);
};

/* Look through this array of symbol tables for a symbol match which
* passes the check function. */
static const struct kernel_symbol *search_symarrays(const struct symsearch *arr,
unsigned int num,
const char *name,
bool gplok,
bool warn,
const unsigned long **crc)
{
unsigned int i;
const struct kernel_symbol *ks;

for (i = 0; i < num; i++) {
ks = lookup_symbol(name, arr[i].start, arr[i].stop);
if (!ks || !arr[i].check(gplok, warn, name))
continue;

if (crc)
*crc = symversion(arr[i].crcs, ks - arr[i].start);
return ks;
}
return NULL;
}

if (gplok)
ks = lookup_symbol(name, __start___ksymtab_unused_gpl,
__stop___ksymtab_unused_gpl);
/* Find a symbol, return value, (optional) crc and (optional) module
* which owns it */
static unsigned long find_symbol(const char *name,
struct module **owner,
const unsigned long **crc,
bool gplok,
bool warn)
{
struct module *mod;
const struct kernel_symbol *ks;
const struct symsearch arr[] = {
{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,
always_ok },
{ __start___ksymtab_gpl, __stop___ksymtab_gpl,
__start___kcrctab_gpl, gpl_only },
{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,
__start___kcrctab_gpl_future, warn_if_not_gpl },
{ __start___ksymtab_unused, __stop___ksymtab_unused,
__start___kcrctab_unused, printk_unused_warning },
{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,
__start___kcrctab_unused_gpl, gpl_only_unused_warning },
};

/* Core kernel first. */
ks = search_symarrays(arr, ARRAY_SIZE(arr), name, gplok, warn, crc);
if (ks) {
printk_unused_warning(name);
*crc = symversion(__start___kcrctab_unused_gpl,
(ks - __start___ksymtab_unused_gpl));
if (owner)
*owner = NULL;
return ks->value;
}

/* Now try modules. */
list_for_each_entry(mod, &modules, list) {
*owner = mod;
ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
struct symsearch arr[] = {
{ mod->syms, mod->syms + mod->num_syms, mod->crcs,
always_ok },
{ mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
mod->gpl_crcs, gpl_only },
{ mod->gpl_future_syms,
mod->gpl_future_syms + mod->num_gpl_future_syms,
mod->gpl_future_crcs, warn_if_not_gpl },
{ mod->unused_syms,
mod->unused_syms + mod->num_unused_syms,
mod->unused_crcs, printk_unused_warning },
{ mod->unused_gpl_syms,
mod->unused_gpl_syms + mod->num_unused_gpl_syms,
mod->unused_gpl_crcs, gpl_only_unused_warning },
};

ks = search_symarrays(arr, ARRAY_SIZE(arr),
name, gplok, warn, crc);
if (ks) {
*crc = symversion(mod->crcs, (ks - mod->syms));
return ks->value;
}

if (gplok) {
ks = lookup_symbol(name, mod->gpl_syms,
mod->gpl_syms + mod->num_gpl_syms);
if (ks) {
*crc = symversion(mod->gpl_crcs,
(ks - mod->gpl_syms));
return ks->value;
}
}
ks = lookup_symbol(name, mod->unused_syms, mod->unused_syms + mod->num_unused_syms);
if (ks) {
printk_unused_warning(name);
*crc = symversion(mod->unused_crcs, (ks - mod->unused_syms));
return ks->value;
}

if (gplok) {
ks = lookup_symbol(name, mod->unused_gpl_syms,
mod->unused_gpl_syms + mod->num_unused_gpl_syms);
if (ks) {
printk_unused_warning(name);
*crc = symversion(mod->unused_gpl_crcs,
(ks - mod->unused_gpl_syms));
return ks->value;
}
}
ks = lookup_symbol(name, mod->gpl_future_syms,
(mod->gpl_future_syms +
mod->num_gpl_future_syms));
if (ks) {
if (!gplok) {
printk(KERN_WARNING "Symbol %s is being used "
"by a non-GPL module, which will not "
"be allowed in the future\n", name);
printk(KERN_WARNING "Please see the file "
"Documentation/feature-removal-schedule.txt "
"in the kernel source tree for more "
"details.\n");
}
*crc = symversion(mod->gpl_future_crcs,
(ks - mod->gpl_future_syms));
if (owner)
*owner = mod;
return ks->value;
}
}

DEBUGP("Failed to find symbol %s\n", name);
return -ENOENT;
}
Expand Down Expand Up @@ -777,10 +786,9 @@ static void print_unload_info(struct seq_file *m, struct module *mod)
void __symbol_put(const char *symbol)
{
struct module *owner;
const unsigned long *crc;

preempt_disable();
if (IS_ERR_VALUE(__find_symbol(symbol, &owner, &crc, 1)))
if (IS_ERR_VALUE(find_symbol(symbol, &owner, NULL, true, false)))
BUG();
module_put(owner);
preempt_enable();
Expand Down Expand Up @@ -924,13 +932,10 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
struct module *mod)
{
const unsigned long *crc;
struct module *owner;

if (IS_ERR_VALUE(__find_symbol("struct_module",
&owner, &crc, 1)))
if (IS_ERR_VALUE(find_symbol("struct_module", NULL, &crc, true, false)))
BUG();
return check_version(sechdrs, versindex, "struct_module", mod,
crc);
return check_version(sechdrs, versindex, "struct_module", mod, crc);
}

/* First part is kernel version, which we ignore. */
Expand Down Expand Up @@ -974,8 +979,8 @@ static unsigned long resolve_symbol(Elf_Shdr *sechdrs,
unsigned long ret;
const unsigned long *crc;

ret = __find_symbol(name, &owner, &crc,
!(mod->taints & TAINT_PROPRIETARY_MODULE));
ret = find_symbol(name, &owner, &crc,
!(mod->taints & TAINT_PROPRIETARY_MODULE), true);
if (!IS_ERR_VALUE(ret)) {
/* use_module can fail due to OOM,
or module initialization or unloading */
Expand Down Expand Up @@ -1376,10 +1381,9 @@ void *__symbol_get(const char *symbol)
{
struct module *owner;
unsigned long value;
const unsigned long *crc;

preempt_disable();
value = __find_symbol(symbol, &owner, &crc, 1);
value = find_symbol(symbol, &owner, NULL, true, true);
if (IS_ERR_VALUE(value))
value = 0;
else if (strong_try_module_get(owner))
Expand All @@ -1402,16 +1406,16 @@ static int verify_export_symbols(struct module *mod)
const unsigned long *crc;

for (i = 0; i < mod->num_syms; i++)
if (!IS_ERR_VALUE(__find_symbol(mod->syms[i].name,
&owner, &crc, 1))) {
if (!IS_ERR_VALUE(find_symbol(mod->syms[i].name,
&owner, &crc, true, false))) {
name = mod->syms[i].name;
ret = -ENOEXEC;
goto dup;
}

for (i = 0; i < mod->num_gpl_syms; i++)
if (!IS_ERR_VALUE(__find_symbol(mod->gpl_syms[i].name,
&owner, &crc, 1))) {
if (!IS_ERR_VALUE(find_symbol(mod->gpl_syms[i].name,
&owner, &crc, true, false))) {
name = mod->gpl_syms[i].name;
ret = -ENOEXEC;
goto dup;
Expand Down

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