Messages in this thread | | | From | (Eric W. Biederman) | Date | Wed, 27 May 2020 09:41:53 -0500 | Subject | Re: [PATCH] proc/base: Skip assignment to len when there is no error on d_path in do_proc_readlink. |
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Kaitao Cheng <pilgrimtao@gmail.com> writes:
> we don't need {len = PTR_ERR(pathname)} when IS_ERR(pathname) is false, > it's better to move it into if(IS_ERR(pathname)){}.
Please look at the generated code.
I believe you will find that your change will generate worse assembly.
Eric
> Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com> > --- > fs/proc/base.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index d86c0afc8a85..9509e0d42610 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -1753,9 +1753,10 @@ static int do_proc_readlink(struct path *path, char __user *buffer, int buflen) > return -ENOMEM; > > pathname = d_path(path, tmp, PAGE_SIZE); > - len = PTR_ERR(pathname); > - if (IS_ERR(pathname)) > + if (IS_ERR(pathname)) { > + len = PTR_ERR(pathname); > goto out; > + } > len = tmp + PAGE_SIZE - 1 - pathname; > > if (len > buflen)
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