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    Subject[PATCH 2/5] MIPS/ptrace: Update mips_get_syscall_arg's return type
    Date
    clang warns:

    arch/mips/include/asm/syscall.h:136:3: error: variable 'ret' is
    uninitialized when used here [-Werror,-Wuninitialized]
    ret |= mips_get_syscall_arg(args++, task, regs, i++);
    ^~~
    arch/mips/include/asm/syscall.h:129:9: note: initialize the variable
    'ret' to silence this warning
    int ret;
    ^
    = 0
    1 error generated.

    It's not wrong; however, it's not an issue in practice because ret is
    only assigned to, not read from. ret could just be initialized to zero
    but looking into it further, ret has been unused since it was first
    added in 2012 so just get rid of it and update mips_get_syscall_arg's
    return type since none of the return values are ever checked. If it is
    ever needed again, this commit can be reverted and ret can be properly
    initialized.

    Fixes: c0ff3c53d4f9 ("MIPS: Enable HAVE_ARCH_TRACEHOOK.")
    Link: https://github.com/ClangBuiltLinux/linux/issues/604
    Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
    ---
    arch/mips/include/asm/syscall.h | 21 +++++++--------------
    1 file changed, 7 insertions(+), 14 deletions(-)

    diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
    index 83bb439597d8..25fa651c937d 100644
    --- a/arch/mips/include/asm/syscall.h
    +++ b/arch/mips/include/asm/syscall.h
    @@ -54,7 +54,7 @@ static inline void mips_syscall_update_nr(struct task_struct *task,
    task_thread_info(task)->syscall = regs->regs[2];
    }

    -static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
    +static inline void mips_get_syscall_arg(unsigned long *arg,
    struct task_struct *task, struct pt_regs *regs, unsigned int n)
    {
    unsigned long usp __maybe_unused = regs->regs[29];
    @@ -63,23 +63,24 @@ static inline unsigned long mips_get_syscall_arg(unsigned long *arg,
    case 0: case 1: case 2: case 3:
    *arg = regs->regs[4 + n];

    - return 0;
    + return;

    #ifdef CONFIG_32BIT
    case 4: case 5: case 6: case 7:
    - return get_user(*arg, (int *)usp + n);
    + get_user(*arg, (int *)usp + n);
    + return;
    #endif

    #ifdef CONFIG_64BIT
    case 4: case 5: case 6: case 7:
    #ifdef CONFIG_MIPS32_O32
    if (test_tsk_thread_flag(task, TIF_32BIT_REGS))
    - return get_user(*arg, (int *)usp + n);
    + get_user(*arg, (int *)usp + n);
    else
    #endif
    *arg = regs->regs[4 + n];

    - return 0;
    + return;
    #endif

    default:
    @@ -126,21 +127,13 @@ static inline void syscall_get_arguments(struct task_struct *task,
    {
    unsigned int i = 0;
    unsigned int n = 6;
    - int ret;

    /* O32 ABI syscall() */
    if (mips_syscall_is_indirect(task, regs))
    i++;

    while (n--)
    - ret |= mips_get_syscall_arg(args++, task, regs, i++);
    -
    - /*
    - * No way to communicate an error because this is a void function.
    - */
    -#if 0
    - return ret;
    -#endif
    + mips_get_syscall_arg(args++, task, regs, i++);
    }

    extern const unsigned long sys_call_table[];
    --
    2.23.0.rc2
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