On Fri, 21 Jun 2024 10:20:36 +0100
Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> wrote:
> On Thu, 20 Jun 2024 20:01:45 +0200
> Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> wrote:
>
> > Sometimes it is desired to produce a single log line for errors.
> > Add a new helper function for such purpose.
> >
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> > ---
> > drivers/firmware/efi/cper.c | 59 +++++++++++++++++++++++++++++++++++++
> > include/linux/cper.h | 3 ++
> > 2 files changed, 62 insertions(+)
> >
> > diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
> > index 7d2cdd9e2227..9bf27af3e870 100644
> > --- a/drivers/firmware/efi/cper.c
> > +++ b/drivers/firmware/efi/cper.c
> > @@ -106,6 +106,65 @@ void cper_print_bits(const char *pfx, unsigned int bits,
> > printk("%s\n", buf);
> > }
> >
> > +/*
>
> It's exported and in a header used by other code, so why not make
> this kernel-doc? /**
>
> > + * cper_bits_to_str - return a string for set bits
> > + * @buf: buffer to store the output string
> > + * @buf_size: size of the output string buffer
> > + * @bits: bit mask
> > + * @strs: string array, indexed by bit position
> > + * @strs_size: size of the string array: @strs
>
> If it had been kernel doc, W=1 would have told you mask is
> missing.
>
> Passing a 0 for mask seems probably not worth while.
> If all bits of the unsigned int are set then people can pass ~0
>
> Or make this cper_bits_to_str_masked() and have
> cper_bits_to_str() that doesn't take a mask.
>
Mask definitely needs docs as I misunderstood it :(
Also needs to be contiguous I think which is also a bit unusual.
> If you do that, some simplifications can be easily made.
>
>
>
> > + *
> > + * add to @buf the bitmask in hexadecimal. Then, for each set bit in @bits,
> > + * add the corresponding string in @strs to @buf.
> > + */
> > +char *cper_bits_to_str(char *buf, int buf_size, unsigned int bits,
>
> Perhaps make bits an unsigned long as then you can use the
> for_each_set_bit() etc.
>
> > + const char * const strs[], unsigned int strs_size,
> > + unsigned int mask)
> > +{
> > + int i, size, first_bit;
> > + int len = buf_size;
> > + const char *start;
> > + char *str = buf;
> > +
> > + if (strs_size < 16)
> > + size = snprintf(str, len, "0x%02x: ", bits);
> > + if (strs_size < 32)
> > + size = snprintf(str, len, "0x%04x: ", bits);
> > +
> > + len -= size;
> > + str += size;
> > +
> > + start = str;
> > +
> > + if (mask) {
> > + first_bit = ffs(mask) - 1;
> > + if (bits & ~mask) {
> > + size = strscpy(str, "reserved bit(s)", len);
> > + len -= size;
> > + str += size;
> > + }
> > + } else {
> > + first_bit = 0;
> > + }
> Might be worth
>
> bits = bits & mask;
>
> Obviously setting bits that aren't in the mask is
> odd though so maybe a warning print if that happens?
> > +
>
>
> for_each_bit_set(i, &bits, strs_size) {
Ah. I'd missed the offset and gotten function name wrong.
i = first_bit
for_each_set_bit_from(i, &bits, strs_size + first_bit)
and look up based on i - first_bit
> ...
>
> }
>
> > + for (i = 0; i < strs_size; i++) {
> > + if (!(bits & (1U << (i + first_bit))))
> > + continue;
> > +
> > + if (*start && len > 0) {
> > + *str = '|';
> > + len--;
> > + str++;
> > + }
> > +
> > + size = strscpy(str, strs[i], len);
> > + len -= size;
> > + str += size;
> > + }
> > + return buf;
> > +}
> > +EXPORT_SYMBOL_GPL(cper_bits_to_str);
> > +
> > static const char * const proc_type_strs[] = {
> > "IA32/X64",
> > "IA64",
> > diff --git a/include/linux/cper.h b/include/linux/cper.h
> > index 265b0f8fc0b3..856e8f00a7fb 100644
> > --- a/include/linux/cper.h
> > +++ b/include/linux/cper.h
> > @@ -584,6 +584,9 @@ const char *cper_mem_err_type_str(unsigned int);
> > const char *cper_mem_err_status_str(u64 status);
> > void cper_print_bits(const char *prefix, unsigned int bits,
> > const char * const strs[], unsigned int strs_size);
> > +char *cper_bits_to_str(char *buf, int buf_size, unsigned int bits,
> > + const char * const strs[], unsigned int strs_size,
> > + unsigned int mask);
> > void cper_mem_err_pack(const struct cper_sec_mem_err *,
> > struct cper_mem_err_compact *);
> > const char *cper_mem_err_unpack(struct trace_seq *,
>
