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author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-25 23:48:30 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-25 23:48:30 (GMT) |
commit | 218ce7351413b8287a80fab1d7b94906a5559f01 (patch) | |
tree | 36ba694491fa39fbde719b889a89cadbedd1f357 /kernel/module.c | |
parent | ec96e2fe954c23a54bfdf2673437a39e193a1822 (diff) | |
download | linux-fsl-qoriq-218ce7351413b8287a80fab1d7b94906a5559f01.tar.xz |
Revert "module: drop the lock while waiting for module to complete initialization."
This reverts commit 480b02df3aa9f07d1c7df0cd8be7a5ca73893455, since
Rafael reports that it causes occasional kernel paging request faults in
load_module().
Dropping the module lock and re-taking it deep in the call-chain is
definitely not the right thing to do. That just turns the mutex from a
lock into a "random non-locking data structure" that doesn't actually
protect what it's supposed to protect.
Requested-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Brandon Philips <brandon@ifup.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/module.c')
-rw-r--r-- | kernel/module.c | 59 |
1 files changed, 22 insertions, 37 deletions
diff --git a/kernel/module.c b/kernel/module.c index 625985e..333fbcc 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -563,26 +563,33 @@ int use_module(struct module *a, struct module *b) struct module_use *use; int no_warn, err; - if (b == NULL || already_uses(a, b)) - return 0; + if (b == NULL || already_uses(a, b)) return 1; /* If we're interrupted or time out, we fail. */ - err = strong_try_module_get(b); + if (wait_event_interruptible_timeout( + module_wq, (err = strong_try_module_get(b)) != -EBUSY, + 30 * HZ) <= 0) { + printk("%s: gave up waiting for init of module %s.\n", + a->name, b->name); + return 0; + } + + /* If strong_try_module_get() returned a different error, we fail. */ if (err) - return err; + return 0; DEBUGP("Allocating new usage for %s.\n", a->name); use = kmalloc(sizeof(*use), GFP_ATOMIC); if (!use) { printk("%s: out of memory loading\n", a->name); module_put(b); - return -ENOMEM; + return 0; } use->module_which_uses = a; list_add(&use->list, &b->modules_which_use_me); no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name); - return 0; + return 1; } EXPORT_SYMBOL_GPL(use_module); @@ -875,7 +882,7 @@ static inline void module_unload_free(struct module *mod) int use_module(struct module *a, struct module *b) { - return strong_try_module_get(b); + return strong_try_module_get(b) == 0; } EXPORT_SYMBOL_GPL(use_module); @@ -1046,39 +1053,17 @@ static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs, struct module *owner; const struct kernel_symbol *sym; const unsigned long *crc; - DEFINE_WAIT(wait); - int err; - long timeleft = 30 * HZ; -again: sym = find_symbol(name, &owner, &crc, !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true); - if (!sym) - return NULL; - - if (!check_version(sechdrs, versindex, name, mod, crc, owner)) - return NULL; - - prepare_to_wait(&module_wq, &wait, TASK_INTERRUPTIBLE); - err = use_module(mod, owner); - if (likely(!err) || err != -EBUSY || signal_pending(current)) { - finish_wait(&module_wq, &wait); - return err ? NULL : sym; - } - - /* Module is still loading. Drop lock and wait. */ - mutex_unlock(&module_mutex); - timeleft = schedule_timeout(timeleft); - mutex_lock(&module_mutex); - finish_wait(&module_wq, &wait); - - /* Module might be gone entirely, or replaced. Re-lookup. */ - if (timeleft) - goto again; - - printk(KERN_WARNING "%s: gave up waiting for init of module %s.\n", - mod->name, owner->name); - return NULL; + /* use_module can fail due to OOM, + or module initialization or unloading */ + if (sym) { + if (!check_version(sechdrs, versindex, name, mod, crc, owner) + || !use_module(mod, owner)) + sym = NULL; + } + return sym; } /* |