lkml.org 
[lkml]   [2010]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 7/8] percpu: add __percpu sparse annotations to hw_breakpoint
    On Tue, Jan 26, 2010 at 11:13:59AM +0900, Tejun Heo wrote:
    > Hello,
    >
    > On 01/26/2010 11:01 AM, Frederic Weisbecker wrote:
    > > So, may be it considers you are applying the address space overriding
    > > to the pointer to the type and not to the type itself.
    > >
    > > Consider:
    > >
    > > int __percpu i;
    > >
    > > What you do above *might* be considered as if SHIFT_PERCPU_PTR
    > > returns something of a type:
    > >
    > > int * __percpu i;
    > >
    > > So the pointer is in the normal address space, but its content is in
    > > __percpu address space.
    > >
    > > What if you do this:
    > >
    > >
    > > #define SHIFT_PERCPU_PTR(__p, __offset) ({ \
    > > __verify_pcpu_ptr((__p)); \
    > > RELOC_HIDE((__p), (__offset)); \
    > > })
    > >
    > > #define per_cpu(var, cpu) \
    > > (typeof(var) __kernel __force)(*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)))
    >
    > arch/x86/kernel/cpu/common.c:1149:20: warning: cast to non-scalar
    > arch/x86/kernel/cpu/common.c:1149:20: error: strange non-value function or array
    > CC arch/x86/kernel/cpu/common.o
    > arch/x86/kernel/cpu/common.c: In function 'cpu_init':
    > arch/x86/kernel/cpu/common.c:1149: error: cast specifies array type
    >
    > Can't cast that way. :-(


    What about this? It doesn't use direct cast to scalar but should
    create a pointer type to kernel space datas:


    #define kernel_space_t(var) \
    (typeof(var) __kernel __force)

    #define SHIFT_PERCPU_PTR(__p, __offset) ({ \
    __verify_pcpu_ptr((__p)); \
    RELOC_HIDE((typeof(*(kernel_space_t(var)) __kernel __force *)(__p), (__offset)); \
    })

    #define per_cpu(var, cpu) \
    (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu)))



    \
     
     \ /
      Last update: 2010-01-26 03:21    [W:0.023 / U:0.084 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site