On 2/12/21 10:27 PM, Mathieu Poirier wrote:
[...]
- if (nr_pages < 2)
return NULL;- buf = kzalloc_node(sizeof(*buf), GFP_KERNEL, trbe_alloc_node(event));
- if (IS_ERR(buf))
return ERR_PTR(-ENOMEM);- pglist = kcalloc(nr_pages, sizeof(*pglist), GFP_KERNEL);
- if (IS_ERR(pglist)) {
kfree(buf);return ERR_PTR(-ENOMEM);- }
- for (i = 0; i < nr_pages; i++)
pglist[i] = virt_to_page(pages[i]);- buf->trbe_base = (unsigned long) vmap(pglist, nr_pages, VM_MAP, PAGE_KERNEL);
- if (IS_ERR((void *)buf->trbe_base)) {
Why not simply make buf->trbe_base a void * instead of having to do all this
There are many arithmetic and comparison operations involving trbe_base element. Hence it might be better to keep it as unsigned long, also to keeps it consistent with other pointers i.e trbe_write, trbe_limit.
That is a fair point. Please add a comment to explain your design choice and make sure the sparse checker is happy with all of it.
Added a comment.
Snippet from $cat drivers/hwtracing/coresight/coresight-trbe.c | grep "trbe_base" There are just two places type casting trbe_base back to (void *).
memset((void *)buf->trbe_base + head, ETE_IGNORE_PACKET, len); return buf->trbe_base + offset; WARN_ON(buf->trbe_write < buf->trbe_base); set_trbe_base_pointer(buf->trbe_base); buf->trbe_base = (unsigned long)vmap(pglist, nr_pages, VM_MAP, PAGE_KERNEL); if (IS_ERR((void *)buf->trbe_base)) { return ERR_PTR(buf->trbe_base); buf->trbe_limit = buf->trbe_base + nr_pages * PAGE_SIZE; buf->trbe_write = buf->trbe_base; vunmap((void *)buf->trbe_base); base = get_trbe_base_pointer(); buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf); if (buf->trbe_limit == buf->trbe_base) { buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf); if (buf->trbe_limit == buf->trbe_base) { offset = get_trbe_limit_pointer() - get_trbe_base_pointer(); buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf); if (buf->trbe_limit == buf->trbe_base) { WARN_ON(buf->trbe_base != get_trbe_base_pointer()); if (get_trbe_write_pointer() == get_trbe_base_pointer())
casting? And IS_ERR() doesn't work with vmap().
Sure, will drop IS_ERR() here.
[...]
+static ssize_t dbm_show(struct device *dev, struct device_attribute *attr, char *buf) +{
- struct trbe_cpudata *cpudata = dev_get_drvdata(dev);
- return sprintf(buf, "%d\n", cpudata->trbe_dbm);
+} +static DEVICE_ATTR_RO(dbm);
What does "dbm" stand for? Looking at the documentation for TRBIDR_EL1.F, I don't see what "dbm" relates to.
I made it up to refer TRBIDR_EL1.F as "Dirty (and Access Flag) Bit Management". Could change it as "afdbm" to be more specific or if it is preferred.
I don't see "afdbm" being a better solution - why not simply "flag"?
Replaced all reference for "dbm" with "flag".