On Wed, Mar 14, 2018 at 04:25:22PM -0700, Dave Jiang wrote:
> Adding helper functions to iterate through sysfs region persistence domain
> attribute. The region will display the domain with the most persistence for
> the
> region. The bus will display the domain attribute with the least persistence
> amongst all the regions. ndctl_bus_get_persistence_domain() and
> ndctl_region_get_persistence_domain are exported. ndctl list will also display
> the region persistence domain as well.
>
> Signed-off-by: Dave Jiang <[email protected]>
In general I think this is more complex than it needs to be. IIUC we have a
1:1 relationship between regions and persistence domains, right? If so, I
don't understand the need for region_pd_foreach(), region_get_first_pd(),
region_get_next_pd(), etc.
Can't we just have one region_get_persistence_domain() which opens
region->path/persistence_domain, parses a string, and is done?
If so, this obviates the need to store a FILE* (persist_fp) in struct
ndctl_region, right? Let's just keep the open/read/close sequence local to
the get() function.
Some other nits below.
> ---
> 0 files changed
>
> diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
> index a165e697..94a1dbcd 100644
> --- a/ndctl/lib/libndctl.c
> +++ b/ndctl/lib/libndctl.c
> @@ -180,6 +180,8 @@ struct ndctl_region {
> } iset;
> FILE *badblocks;
> struct badblock bb;
> + FILE *persist_fp;
> + unsigned int persist_domain;
Throughout I think it'd add clarity to use a named enum for the
PERSISTENCE_CPU_CACHE type defines, instead of passing around unsigned ints.
See ndctl_pfn_get_location() et al. for an example of what I mean - this
disambiguates your enum from an error return value, for example.
Tiny nit: you spell out "persistence" for both the function names and for the
PERSISTENCE_CPU_CACHE type defines, but for these members you shorten to
"persist". My vote is to spell it out always so it's more consistent.
> };
>
> /**
> @@ -916,6 +918,17 @@ NDCTL_EXPORT struct ndctl_bus
> *ndctl_bus_get_by_provider(struct ndctl_ctx *ctx,
> return NULL;
> }
>
> +NDCTL_EXPORT unsigned int
> +ndctl_bus_get_persistence_domain(struct ndctl_bus *bus)
> +{
> + struct ndctl_region *region;
> +
> + /* iterate through region to get the region persist domain */
> + ndctl_region_foreach(bus, region) {}
I don't understand why you need to loop though all the regions in the bus?
ndctl_region_foreach() ends up calling
ndctl_region_get_first()=>regions_init(), which I think is what you care
about, right? No need for the looping.
> +static int region_persistence_init(struct ndctl_region *region)
> +{
> + struct ndctl_ctx *ctx = ndctl_region_get_ctx(region);
> + char *pd_path;
> + int rc = 0;
> +
> + if (region->persist_fp) {
> + fclose(region->persist_fp);
> + region->persist_fp = NULL;
> + }
> +
> + if (asprintf(&pd_path, "%s/persistence_domain",
> + region->region_path) < 0) {
> + rc = -errno;
> + err(ctx, "region persist domain path allocation failure\n");
> + return rc;
> + }
> +
> + region->persist_fp = fopen(pd_path, "re");
> + if (!region->persist_fp) {
> + rc = -errno;
> + free(pd_path);
> + return rc;
no need for the free() and return lines - just fall thru.
> + }
> +
> + free(pd_path);
> + return rc;
> +}
<>
> diff --git a/ndctl/libndctl.h b/ndctl/libndctl.h
> index f3a27411..be5b196c 100644
> --- a/ndctl/libndctl.h
> +++ b/ndctl/libndctl.h
> @@ -115,6 +115,7 @@ int ndctl_bus_is_cmd_supported(struct ndctl_bus *bus, int
> cmd);
> unsigned int ndctl_bus_get_revision(struct ndctl_bus *bus);
> unsigned int ndctl_bus_get_id(struct ndctl_bus *bus);
> const char *ndctl_bus_get_provider(struct ndctl_bus *bus);
> +unsigned int ndctl_bus_get_persistence_domain(struct ndctl_bus *bus);
> int ndctl_bus_wait_probe(struct ndctl_bus *bus);
> int ndctl_bus_wait_for_scrub_completion(struct ndctl_bus *bus);
> unsigned int ndctl_bus_get_scrub_count(struct ndctl_bus *bus);
> @@ -305,6 +306,14 @@ struct badblock {
> unsigned long long offset;
> unsigned int len;
> };
> +
> +enum {
> + PERSISTENCE_NONE = 0,
> +/* order these in distance to CPU persistence domain */
> + PERSISTENCE_CPU_CACHE,
> + PERSISTENCE_MEM_CTRL,
> +};
I don't think we should have a single value that means "unset" and "no
persistence". Meaning, if we have 3 regions on a bus, and 2 report
PERSISTENCE_NONE and one reports PERSISTENCE_CPU_CACHE, won't this current
code report PERSISTENCE_CPU_CACHE?
I think you can solve this and shorten this type of check in add_region():
if (region->bus->persist_domain == 0 ||
region->bus->persist_domain < pd)
region->bus->persist_domain = pd;
To just:
if (region->bus->persist_domain > pd)
region->bus->persist_domain = pd;
By just reordering them and defining
enum {
PERSISTENCE_NONE = 0,
PERSISTENCE_MEM_CTRL,
PERSISTENCE_CPU_CACHE,
PERSISTENCE_UNKNOWN,
};
and initializing things to PERSISTENCE_UNKNOWN.
> +
> struct ndctl_region;
> struct ndctl_region *ndctl_region_get_first(struct ndctl_bus *bus);
> struct ndctl_region *ndctl_region_get_next(struct ndctl_region *region);
> @@ -318,6 +327,7 @@ struct badblock *ndctl_region_get_next_badblock(struct
> ndctl_region *region);
> for (badblock = ndctl_region_get_first_badblock(region); \
> badblock != NULL; \
> badblock = ndctl_region_get_next_badblock(region))
> +
unrelated whitespace change.
_______________________________________________
Linux-nvdimm mailing list
[email protected]
https://lists.01.org/mailman/listinfo/linux-nvdimm
