On Wed, Jun 16, 2021 at 06:02:47AM +0200, Christoph Hellwig wrote:
> > +#define verify_size(name, alignsize, enabled) { \
> > + long _##name_; \
> > + if (enabled) \
> > + _##name_ = check_size(name, alignsize); \
> > + else \
> > + _##name_ = 0; \
> > + /* synchronize visible module parameters to result. */ \
> > + name = _##name_ / 1024; \
> > + dev->zone.name = _##name_; \
> > + }
>
> The formatting here looks weird between the two-tab indent and the
> opening brace on the macro definition line.
I can adjust that, sure.
>
> > - if (!dev || !dev->total_size || !dev->read || !dev->write) {
> > + if (!dev || !dev->zone.total_size || !dev->zone.read || !dev->zone.write) {
> > if (!dev)
> > - pr_err("NULL device info\n");
> > + pr_err("NULL pstore_device_info\n");
> > else {
> > - if (!dev->total_size)
> > + if (!dev->zone.total_size)
> > pr_err("zero sized device\n");
> > - if (!dev->read)
> > + if (!dev->zone.read)
> > pr_err("no read handler for device\n");
> > - if (!dev->write)
> > + if (!dev->zone.write)
> > pr_err("no write handler for device\n");
> > }
>
> This still looks odd to me. Why not the somewhat more verbose but
> much more obvious:
>
> if (!dev) {
> pr_err("NULL pstore_device_info\n");
> return -EINVAL;
> }
> if (!dev->zone.total_size) {
> pr_err("zero sized device\n");
> return -EINVAL;
> }
> ...
Will do.
> > - dev.total_size = i_size_read(I_BDEV(psblk_file->f_mapping->host)->bd_inode);
> > + dev->zone.total_size = i_size_read(I_BDEV(psblk_file->f_mapping->host)->bd_inode);
>
> This is starting to be unreadable long. A local variable for the inode
> might be nice, as that can also be used in the ISBLK check above.
Fair enough; will change.
> > + if (!pstore_device_info && best_effort && blkdev[0]) {
> > + struct pstore_device_info *best_effort_dev;
> > +
> > + best_effort_dev = kzalloc(sizeof(*best_effort_dev), GFP_KERNEL);
> > + if (!best_effort) {
> > + ret = -ENOMEM;
> > + goto unlock;
> > + }
> > + best_effort_dev->zone.read = psblk_generic_blk_read;
> > + best_effort_dev->zone.write = psblk_generic_blk_write;
> > +
> > + ret = __register_pstore_blk(best_effort_dev,
> > + early_boot_devpath(blkdev));
> > + if (ret)
> > + kfree(best_effort_dev);
> > + else
> > + pr_info("attached %s (%zu) (no dedicated panic_write!)\n",
> > + blkdev, best_effort_dev->zone.total_size);
>
> Maybe split this into a little helper?
>
> > + /* Unregister and free the best_effort device. */
> > + if (psblk_file) {
> > + struct pstore_device_info *dev = pstore_device_info;
> > +
> > + __unregister_pstore_device(dev);
> > + kfree(dev);
> > + fput(psblk_file);
> > + psblk_file = NULL;
> > }
>
> Same.
I guess? I don't feel strongly one way or another.
>
> > + /* If we've been asked to unload, unregister any registered device. */
> > + if (pstore_device_info)
> > + __unregister_pstore_device(pstore_device_info);
>
> Won't this double unregister pstore_device_info?
No, __unregister_pstore_device() will NULL pstore_device_info.
>
> > struct pstore_device_info {
> > - unsigned long total_size;
> > unsigned int flags;
> > - pstore_zone_read_op read;
> > - pstore_zone_write_op write;
> > - pstore_zone_erase_op erase;
> > - pstore_zone_write_op panic_write;
> > + struct pstore_zone_info zone;
> > };
>
> Given that flags is only used inside of __register_pstore_device
> why not kill this struct and just pass it explicitly?
Because of the mess pstore's internal APIs used to be. :) It's likely
other things will get added here in the future, and I don't want to
have to repeat the kind of argument passing games that used to exist in
this code.
--
Kees Cook
