On Thu, 2013-12-12 at 10:27 +1100, Ryan Mallon wrote:
> On 11/12/13 16:12, Joe Perches wrote:
> > seq_printf and seq_puts returns are often misused.
> >
> > Instead of checking the seq_printf or seq_puts return,
> > add a new seq_overflow function to test if a seq_file has
> > overflowed the available buffer space.
> >
> > This will eventually allow seq_printf and seq_puts to be
> > converted to have a void return instead of the int return
> > that is often assumed to have a size_t value instead of an
> > error/no-error value.
> >
> > Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>
> > ---
> > fs/seq_file.c | 15 ++++++++-------
> > include/linux/seq_file.h | 2 ++
> > 2 files changed, 10 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/seq_file.c b/fs/seq_file.c
> > index 1d641bb..aab0736 100644
> > --- a/fs/seq_file.c
> > +++ b/fs/seq_file.c
> > @@ -14,16 +14,17 @@
> > #include <asm/uaccess.h>
> > #include <asm/page.h>
> >
> > -
> > -/*
> > - * seq_files have a buffer which can may overflow. When this happens a larger
> > - * buffer is reallocated and all the data will be printed again.
> > - * The overflow state is true when m->count == m->size.
> > +/**
> > + * seq_overflow - test if a seq_file has overflowed the space available
> > + * @m: the seq_file handle
> > + *
> > + * Returns -1 when an overflow has occurred, 0 otherwise.
> > */
> > -static bool seq_overflow(struct seq_file *m)
> > +int seq_overflow(struct seq_file *m)
> > {
> > - return m->count == m->size;
> > + return m->count == m->size ? -1 : 0;
> > }
> > +EXPORT_SYMBOL(seq_overflow);
>
> What is the reasoning in making this return int instead of bool? Having
> it return int encourages people to do:
>
> return seq_overflow(s);
>
> When used in seq_file functions will return -EPERM (-1) to user-space,
> which is confusing. It should probably return bool and let the caller
> sort out the correct error to return.
It was intended to make the return from seq_printf the same.
Anyway, the patch series is out of date (see Al's comments).
I'll update it later unless you or someone else does it first.
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