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112 lines
3.3 KiB
112 lines
3.3 KiB
From: Jeff Mahoney <jeffm@suse.com>
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Subject: init: move populate_rootfs back to start_kernel
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References: bnc#533555
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Patch-mainline: Probably never
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Mainline commit 8d610dd5 introduced the rootfs_initcall and moved
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populate_rootfs out of start_kernel. This was because of issues
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with userspace helpers being executed way too early. Things like
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pipes weren't initialized yet and users were seeing Oopses or
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unpredictable behavior in certain circumstances.
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The fix worked by causing the execve to fail because it couldn't lookup
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the helper in the file system since the file system wasn't populate yet.
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It turns out that's a really late place to fail since the entire
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usermodehelper infrastructure depends on a work queue that is already
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checked to see if it has been initialized. We can fail earlier without
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having to fork threads that will ultimately fail.
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This patch moves populate_rootfs back to start_kernel and avoids the
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race against a very early userspace by moving the initialization of
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khelper_wq to rootfs_initcall.
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This may seem like a small win, but it is essential for my next patch
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which adds the ability to override ACPI tables at boot-time.
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Signed-off-by: Jeff Mahoney <jeffm@suse.com>
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---
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include/linux/init.h | 1 +
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include/linux/kmod.h | 2 --
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init/initramfs.c | 3 +--
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init/main.c | 10 +++++++++-
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kernel/kmod.c | 4 +++-
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5 files changed, 14 insertions(+), 6 deletions(-)
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--- a/include/linux/init.h
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+++ b/include/linux/init.h
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@@ -146,6 +146,7 @@ extern unsigned int reset_devices;
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/* used by init/main.c */
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void setup_arch(char **);
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void prepare_namespace(void);
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+int populate_rootfs(void);
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extern void (*late_time_init)(void);
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--- a/include/linux/kmod.h
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+++ b/include/linux/kmod.h
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@@ -109,8 +109,6 @@ call_usermodehelper(char *path, char **a
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NULL, NULL, NULL);
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}
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-extern void usermodehelper_init(void);
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-
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extern int usermodehelper_disable(void);
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extern void usermodehelper_enable(void);
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--- a/init/initramfs.c
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+++ b/init/initramfs.c
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@@ -714,7 +714,7 @@ static void __init clean_rootfs(void)
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}
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#endif
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-static int __init populate_rootfs(void)
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+int __init populate_rootfs(void)
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{
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char *err = unpack_to_rootfs(__initramfs_start,
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__initramfs_end - __initramfs_start);
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@@ -754,4 +754,3 @@ static int __init populate_rootfs(void)
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}
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return 0;
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}
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-rootfs_initcall(populate_rootfs);
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--- a/init/main.c
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+++ b/init/main.c
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@@ -696,6 +696,15 @@ asmlinkage void __init start_kernel(void
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check_bugs();
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+ /*
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+ * Do this before starting ACPI so we can read-in
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+ * override tables before the tables are actually
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+ * loaded. The usermode helper won't be initialized
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+ * until much later so we don't race against things
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+ * calling out to userspace.
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+ */
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+ populate_rootfs();
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+
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acpi_early_init(); /* before LAPIC and SMP init */
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sfi_init_late();
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@@ -793,7 +802,6 @@ static void __init do_initcalls(void)
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static void __init do_basic_setup(void)
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{
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cpuset_init_smp();
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- usermodehelper_init();
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init_tmpfs();
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driver_init();
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init_irq_proc();
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--- a/kernel/kmod.c
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+++ b/kernel/kmod.c
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@@ -416,8 +416,10 @@ unlock:
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}
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EXPORT_SYMBOL(call_usermodehelper_exec);
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-void __init usermodehelper_init(void)
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+static int __init usermodehelper_init(void)
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{
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khelper_wq = create_singlethread_workqueue("khelper");
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BUG_ON(!khelper_wq);
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+ return 0;
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}
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+rootfs_initcall(usermodehelper_init);
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