Messages in this thread | | | Subject | Re: [PATCH -mm 1/2] kexec jump -v12: kexec jump | From | Huang Ying <> | Date | Wed, 09 Jul 2008 09:12:42 +0800 |
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Hi, Pavel,
On Tue, 2008-07-08 at 12:40 +0200, Pavel Machek wrote: > Hi! > > > > > @@ -1411,3 +1421,50 @@ static int __init crash_save_vmcoreinfo_ > > > > } > > > > > > > > module_init(crash_save_vmcoreinfo_init) > > > > + > > > > +/** > > > > + * kernel_kexec - reboot the system > > > > > Really? > > > > I will change the comments to reflect the changes to kernel_kexec. > > > > > > + * Move into place and start executing a preloaded standalone > > > > + * executable. If nothing was preloaded return an error. > > > > + */ > > > > +int kernel_kexec(void) > > > > +{ > > > > + int error = 0; > > > > + > > > > + if (xchg(&kexec_lock, 1)) > > > > + return -EBUSY; > > > > > > That's quite a strange way to provide a lock. mutex_trylock? > > > > I think this is because kexec_lock is used by crash_kexec() too, which > > may be called in some extreme environment, such as during panic(). > > > > > > + if (!kexec_image) { > > > > + error = -EINVAL; > > > > + goto Unlock; > > > > + } > > > > + > > > > + if (kexec_image->preserve_context) { > > > > +#ifdef CONFIG_KEXEC_JUMP > > > > + local_irq_disable(); > > > > + save_processor_state(); > > > > > > #else > > > BUG() > > > > > > ...because otherwise you silently do nothing? > > > > > > > +#endif > > > > If CONFIG_KEXEC_JUMP is defined, kexec_image->preserve_context will > > always be 0. So current code is safe. Here, #ifdef is used to resolve > > the dependency issue. For example, save_processor_state() may be > > undefined if CONFIG_KEXEC_JUMP is not defined. > > Move the #ifdef outside the if (), then, so this is clear?
I think this is reasonable, I will do it.
> Actually, if preserve_context is always zero in !KEXEC_JUMP case, it > might make sense to remove whole variable...
I think this will add too many #ifndef CONFIG_KEXEC_JUMP ... #endif that is necessary. The memory and performance gain is too little to compensate the code readability reduction.
Best Regards, Huang Ying
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