On Tue, Mar 26, 2019 at 04:33:00PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> The fdt_get_max_phandle() function has some shortcomings. On one hand it
> returns a uint32_t phandle value via a signed return value.
Uh.. no it doesn't..
> This means a
> caller has to explicitly cast the return value to a uint32_t and perform
> explicit checks against the error code (uint32_t)-1. In addition, the -1
> is the only error code that can be returned, so a caller cannot tell the
> difference between the various failures.
>
> Fix this by adding a new fdt_find_max_phandle() function that returns an
> error code on failure and 0 on success, just like other APIs, and stores
> the maximum phandle value in an output argument on success.
>
> This also refactors fdt_get_max_phandle() to use the new function. Add a
> note pointing out that the new fdt_find_max_phandle() function should be
> preferred over fdt_get_max_phandle().
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
I've applied the series, but adjusted the commit message above for
accuracy. I'm also planning on some followup cleanups which may
change things up a bit more.
> ---
> Changes in v4:
> - new patch
>
> libfdt/fdt_ro.c | 44 +++++++++++++++++++++++++++++---------------
> libfdt/libfdt.h | 16 ++++++++++++++++
> libfdt/libfdt_env.h | 1 +
> libfdt/version.lds | 1 +
> tests/get_phandle.c | 9 +++++++++
> 5 files changed, 56 insertions(+), 15 deletions(-)
>
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index eafc14282892..1d0335ee7188 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -144,32 +144,46 @@ static int fdt_string_eq_(const void *fdt, int stroffset,
> return p && (slen == len) && (memcmp(p, s, len) == 0);
> }
>
> -uint32_t fdt_get_max_phandle(const void *fdt)
> +int fdt_find_max_phandle(const void *fdt, uint32_t *phandle)
> {
> - uint32_t max_phandle = 0;
> - int offset;
> + uint32_t max = 0;
> + int offset = -1;
>
> - for (offset = fdt_next_node(fdt, -1, NULL);;
> - offset = fdt_next_node(fdt, offset, NULL)) {
> - uint32_t phandle;
> + while (true) {
> + uint32_t value;
>
> - if (offset == -FDT_ERR_NOTFOUND)
> - return max_phandle;
> + offset = fdt_next_node(fdt, offset, NULL);
> + if (offset < 0) {
> + if (offset == -FDT_ERR_NOTFOUND)
> + break;
>
> - if (offset < 0)
> - return (uint32_t)-1;
> + return offset;
> + }
>
> - phandle = fdt_get_phandle(fdt, offset);
> - if (phandle == (uint32_t)-1)
> - continue;
> + value = fdt_get_phandle(fdt, offset);
>
> - if (phandle > max_phandle)
> - max_phandle = phandle;
> + if (value > max)
> + max = value;
> }
>
> + if (phandle)
> + *phandle = max;
> +
> return 0;
> }
>
> +uint32_t fdt_get_max_phandle(const void *fdt)
> +{
> + uint32_t phandle;
> + int err;
> +
> + err = fdt_find_max_phandle(fdt, &phandle);
> + if (err < 0)
> + return (uint32_t)-1;
> +
> + return phandle;
> +}
> +
> static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
> {
> int offset = n * sizeof(struct fdt_reserve_entry);
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index a470d1df6d2a..6fce659fd279 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -361,6 +361,20 @@ const char *fdt_get_string(const void *fdt, int stroffset, int *lenp);
> */
> const char *fdt_string(const void *fdt, int stroffset);
>
> +/**
> + * fdt_find_max_phandle - find and return the highest phandle in a tree
> + * @fdt: pointer to the device tree blob
> + * @phandle: return location for the highest phandle value found in the tree
> + *
> + * fdt_find_max_phandle() finds the highest phandle value in the given device
> + * tree. The value returned in @phandle is only valid if the function returns
> + * success.
> + *
> + * returns:
> + * 0 on success or a negative error code on failure
> + */
> +int fdt_find_max_phandle(const void *fdt, uint32_t *phandle);
> +
> /**
> * fdt_get_max_phandle - retrieves the highest phandle in a tree
> * @fdt: pointer to the device tree blob
> @@ -369,6 +383,8 @@ const char *fdt_string(const void *fdt, int stroffset);
> * device tree. This will ignore badly formatted phandles, or phandles
> * with a value of 0 or -1.
> *
> + * This function is deprecated in favour of fdt_find_max_phandle().
> + *
> * returns:
> * the highest phandle on success
> * 0, if no phandle was found in the device tree
> diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
> index eb2053845c9c..4d1cdfa58547 100644
> --- a/libfdt/libfdt_env.h
> +++ b/libfdt/libfdt_env.h
> @@ -52,6 +52,7 @@
> * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> */
>
> +#include <stdbool.h>
> #include <stddef.h>
> #include <stdint.h>
> #include <stdlib.h>
> diff --git a/libfdt/version.lds b/libfdt/version.lds
> index a5fe62d5c5ff..87bbb2fe54d3 100644
> --- a/libfdt/version.lds
> +++ b/libfdt/version.lds
> @@ -66,6 +66,7 @@ LIBFDT_1.2 {
> fdt_resize;
> fdt_overlay_apply;
> fdt_get_string;
> + fdt_find_max_phandle;
> fdt_get_max_phandle;
> fdt_check_full;
> fdt_setprop_placeholder;
> diff --git a/tests/get_phandle.c b/tests/get_phandle.c
> index 22bd7b81b3f0..6973ee4caa17 100644
> --- a/tests/get_phandle.c
> +++ b/tests/get_phandle.c
> @@ -46,6 +46,7 @@ int main(int argc, char *argv[])
> {
> uint32_t max;
> void *fdt;
> + int err;
>
> test_init(argc, argv);
> fdt = load_blob_arg(argc, argv);
> @@ -54,6 +55,14 @@ int main(int argc, char *argv[])
> check_phandle(fdt, "/subnode@2", PHANDLE_1);
> check_phandle(fdt, "/subnode@2/subsubnode@0", PHANDLE_2);
>
> + err = fdt_find_max_phandle(fdt, &max);
> + if (err < 0)
> + FAIL("fdt_find_max_phandle returned %d instead of 0\n", err);
> +
> + if (max != PHANDLE_2)
> + FAIL("fdt_find_max_phandle found 0x%x instead of 0x%x", max,
> + PHANDLE_2);
> +
> max = fdt_get_max_phandle(fdt);
> if (max != PHANDLE_2)
> FAIL("fdt_get_max_phandle returned 0x%x instead of 0x%x\n",
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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