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.
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) {
...
}
> + 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 *,
