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Message-Id: <20070822220341.7926F241@kernel>
Date: Wed, 22 Aug 2007 15:03:41 -0700
From: Dave Hansen <haveblue@...ibm.com>
To: greg@...ah.com
Cc: linux-kernel@...r.kernel.org, michal.k.k.piotrowski@...il.com,
akpm@...ux-foundation.org, Dave Hansen <haveblue@...ibm.com>
Subject: [PATCH] make kobject dynamic allocation check use kallsyms_lookup()
One of the top ten sysfs problems is that users use statically
allocated kobjects. This patch reminds them that this is a
naughty thing.
One _really_ nice thing this patch does, is us the kallsyms
mechanism to print out exactly which symbol is being complained
about:
The kobject at, or inside 'statickobj.2'@(0xc040d020) is not dynamically allocated.
This patch replaces the previous implementation's use of a
_sdata symbol in favor of using kallsyms_lookup(). If a
kobject's address is a resolvable symbol, then it isn't
dynamically allocated.
The one exception to this is init symbols. The patch also
checks to see whether __init memory has been freed and if
it has will allow kobjects in those sections.
Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---
lxc-dave/arch/i386/kernel/vmlinux.lds.S | 2 --
lxc-dave/include/linux/init.h | 1 +
lxc-dave/init/main.c | 9 +++++++++
lxc-dave/lib/kobject.c | 31 ++++++++++++++++++++++---------
4 files changed, 32 insertions(+), 11 deletions(-)
diff -puN lib/kobject.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup lib/kobject.c
--- lxc/lib/kobject.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700
+++ lxc-dave/lib/kobject.c 2007-08-22 14:51:50.000000000 -0700
@@ -139,23 +139,36 @@ static int ptr_in_range(void *ptr, void
return 0;
}
-static void verify_dynamic_kobject_allocation(struct kobject *kobj)
+void verify_dynamic_kobject_allocation(struct kobject *kobj)
{
- if (ptr_in_range(kobj, &_sdata[0], &_edata[0]))
- goto warn;
- if (ptr_in_range(kobj, &__bss_start[0], &__bss_stop[0]))
- goto warn;
- return;
-warn:
+ char *namebuf;
+ const char *ret;
+
+ namebuf = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
+ ret = kallsyms_lookup((unsigned long)kobj, NULL, NULL, NULL,
+ namebuf);
+ /*
+ * This is the X86_32-only part of this function.
+ * This is here because it is valid to have a kobject
+ * in an __init section, but only after those
+ * sections have been freed back to the dynamic pool.
+ */
+ if (!initmem_now_dynamic &&
+ ptr_in_range(kobj, __init_begin, __init_end))
+ goto out;
+ if (!ret || !strlen(ret))
+ goto out;
pr_debug("---- begin silly warning ----\n");
pr_debug("This is a janitorial warning, not a kernel bug.\n");
#ifdef CONFIG_DEBUG_KOBJECT
- print_symbol("The kobject at, or inside %s is not dynamically allocated.\n",
- (unsigned long)kobj);
+ pr_debug("The kobject at, or inside '%s'@(0x%p) is not dynamically allocated.\n",
+ namebuf, kobj);
#endif
pr_debug("kobjects must be dynamically allocated, not static\n");
/* dump_stack(); */
pr_debug("---- end silly warning ----\n");
+out:
+ kfree(namebuf);
}
#else
static void verify_dynamic_kobject_allocation(struct kobject *kobj)
diff -L sre -puN /dev/null /dev/null
diff -puN arch/i386/kernel/vmlinux.lds.S~make-kobject-allocation-debugging-check-use-kallsyms_lookup arch/i386/kernel/vmlinux.lds.S
--- lxc/arch/i386/kernel/vmlinux.lds.S~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700
+++ lxc-dave/arch/i386/kernel/vmlinux.lds.S 2007-08-22 14:51:50.000000000 -0700
@@ -71,8 +71,6 @@ SECTIONS
__tracedata_end = .;
}
- _sdata = .; /* End of text section */
-
RODATA
/* writeable */
diff -puN init/main.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup init/main.c
--- lxc/init/main.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700
+++ lxc-dave/init/main.c 2007-08-22 14:51:50.000000000 -0700
@@ -771,12 +771,21 @@ static void run_init_process(char *init_
kernel_execve(init_filename, argv_init, envp_init);
}
+/*
+ * __init/__init_data sections are turned into normal
+ * dynamically allocated memory later in boot. When
+ * this is 0, the memory is for the __init purposes,
+ * when it it some other value, the memory is dynamic.
+ */
+int initmem_now_dynamic;
+
/* This is a non __init function. Force it to be noinline otherwise gcc
* makes it inline to init() and it becomes part of init.text section
*/
static int noinline init_post(void)
{
free_initmem();
+ initmem_now_dynamic = 1;
unlock_kernel();
mark_rodata_ro();
system_state = SYSTEM_RUNNING;
diff -puN lib/Makefile~make-kobject-allocation-debugging-check-use-kallsyms_lookup lib/Makefile
diff -puN include/linux/kernel.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup include/linux/kernel.h
diff -puN arch/i386/mm/init.c~make-kobject-allocation-debugging-check-use-kallsyms_lookup arch/i386/mm/init.c
diff -puN include/linux/init.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup include/linux/init.h
--- lxc/include/linux/init.h~make-kobject-allocation-debugging-check-use-kallsyms_lookup 2007-08-22 14:51:50.000000000 -0700
+++ lxc-dave/include/linux/init.h 2007-08-22 14:51:50.000000000 -0700
@@ -83,6 +83,7 @@ extern initcall_t __security_initcall_st
extern char __initdata boot_command_line[];
extern char *saved_command_line;
extern unsigned int reset_devices;
+extern int initmem_now_dynamic;
/* used by init/main.c */
void setup_arch(char **);
_
-
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