From 66f5ddf30a59f811818656cb2833c80da0340cfa Mon Sep 17 00:00:00 2001 From: "Luck, Tony" Date: Thu, 3 Nov 2011 11:46:47 -0700 Subject: [PATCH] x86/mce: Make mce_chrdev_ops 'static const' Arjan would like to make struct file_operations const, but mce-inject directly writes to the mce_chrdev_ops to install its write handler. In an ideal world mce-inject would have its own character device, but we have a sizable legacy of test scripts that hardwire "/dev/mcelog", so it would be painful to switch to a separate device now. Instead, this patch switches to a stub function in the mce code, with a registration helper that mce-inject can call when it is loaded. Note that this would also allow for a sane process to allow mce-inject to be unloaded again (with an unregister function, and appropriate module_{get,put}() calls), but that is left for potential future patches. Reported-by: Arjan van de Ven Signed-off-by: Tony Luck Link: http://lkml.kernel.org/r/4eb2e1971326651a3b@agluck-desktop.sc.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/mce.h | 5 ++++- arch/x86/kernel/cpu/mcheck/mce-inject.c | 2 +- arch/x86/kernel/cpu/mcheck/mce.c | 25 ++++++++++++++++++++++--- 3 files changed, 27 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h index c9321f34e55..0e8ae57d365 100644 --- a/arch/x86/include/asm/mce.h +++ b/arch/x86/include/asm/mce.h @@ -201,7 +201,10 @@ int mce_notify_irq(void); void mce_notify_process(void); DECLARE_PER_CPU(struct mce, injectm); -extern struct file_operations mce_chrdev_ops; + +extern void register_mce_write_callback(ssize_t (*)(struct file *filp, + const char __user *ubuf, + size_t usize, loff_t *off)); /* * Exception handler diff --git a/arch/x86/kernel/cpu/mcheck/mce-inject.c b/arch/x86/kernel/cpu/mcheck/mce-inject.c index 6199232161c..319882ef848 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-inject.c +++ b/arch/x86/kernel/cpu/mcheck/mce-inject.c @@ -208,7 +208,7 @@ static int inject_init(void) if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL)) return -ENOMEM; printk(KERN_INFO "Machine check injector initialized\n"); - mce_chrdev_ops.write = mce_write; + register_mce_write_callback(mce_write); register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify"); return 0; diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 362056aefeb..2af127d4c3d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1634,16 +1634,35 @@ static long mce_chrdev_ioctl(struct file *f, unsigned int cmd, } } -/* Modified in mce-inject.c, so not static or const */ -struct file_operations mce_chrdev_ops = { +static ssize_t (*mce_write)(struct file *filp, const char __user *ubuf, + size_t usize, loff_t *off); + +void register_mce_write_callback(ssize_t (*fn)(struct file *filp, + const char __user *ubuf, + size_t usize, loff_t *off)) +{ + mce_write = fn; +} +EXPORT_SYMBOL_GPL(register_mce_write_callback); + +ssize_t mce_chrdev_write(struct file *filp, const char __user *ubuf, + size_t usize, loff_t *off) +{ + if (mce_write) + return mce_write(filp, ubuf, usize, off); + else + return -EINVAL; +} + +static const struct file_operations mce_chrdev_ops = { .open = mce_chrdev_open, .release = mce_chrdev_release, .read = mce_chrdev_read, + .write = mce_chrdev_write, .poll = mce_chrdev_poll, .unlocked_ioctl = mce_chrdev_ioctl, .llseek = no_llseek, }; -EXPORT_SYMBOL_GPL(mce_chrdev_ops); static struct miscdevice mce_chrdev_device = { MISC_MCELOG_MINOR,