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SubjectRe: [v2,2/4] Simplify catalog_read()
Date
On Wed, 2014-24-09 at 19:24:39 UTC, sukadev@linux.vnet.ibm.com wrote:
> catalog_read() implements the read interface for the sysfs file
>
> /sys/bus/event_source/devices/hv_24x7/interface/catalog
>
> It essentially takes a buffer, an offset and count as parameters
> to the read() call. It makes a hypervisor call to read a specific
> page from the catalog and copy the required bytes into the given
> buffer. Each call to catalog_read() returns at most one 4K page.
>
> Given these requirements, we should be able to simplify the
> catalog_read().
>
> diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
> index 2f2215c..9427ef7 100644
> --- a/arch/powerpc/perf/hv-24x7.c
> +++ b/arch/powerpc/perf/hv-24x7.c
> @@ -185,6 +105,8 @@ static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
> ssize_t ret = 0;
> size_t catalog_len = 0, catalog_page_len = 0, page_count = 0;
> loff_t page_offset = 0;
> + loff_t offset_in_page;
> + size_t copy_len;
> uint64_t catalog_version_num = 0;
> void *page = kmem_cache_alloc(hv_page_cache, GFP_USER);
> struct hv_24x7_catalog_page_0 *page_0 = page;
> @@ -203,6 +125,7 @@ static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
>
> page_offset = offset / 4096;
> page_count = count / 4096;

I don't see where page_count is used.

> + offset_in_page = count % 4096;

Shouldn't offset_in_page be based on offset ?

cheers


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