Messages in this thread | | | From | Michael Ellerman <> | Subject | Re: [v2,2/4] Simplify catalog_read() | Date | Wed, 1 Oct 2014 10:32:13 +1000 (EST) |
| |
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
| |