Messages in this thread | | | Subject | Re: [PATCH 01/17] MTD: create lockless versions of {get,put}_mtd_device This will be used to resolve deadlock in block translation layer. | From | Maxim Levitsky <> | Date | Tue, 09 Feb 2010 19:23:26 +0200 |
| |
On Tue, 2010-02-09 at 18:14 +0100, Peter Zijlstra wrote: > On Tue, 2010-02-09 at 18:57 +0200, Maxim Levitsky wrote: > > These functions can be used as long as we don't need access to global mtd table, but have > > a pointer to the mtd device. > > > > Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com> > > --- > > drivers/mtd/mtdcore.c | 60 ++++++++++++++++++++++++++++++---------------- > > include/linux/mtd/mtd.h | 3 +- > > 2 files changed, 41 insertions(+), 22 deletions(-) > > > +int __get_mtd_device(struct mtd_info *mtd) > > +{ > > + int err; > > + > > + if (!try_module_get(mtd->owner)) > > + return -ENODEV; > > + > > + if (mtd->get_device) { > > + > > + err = mtd->get_device(mtd); > > + > > + if (err) { > > + module_put(mtd->owner); > > + return err; > > + } > > + } > > + mtd->usecount++; > > + return 0; > > } > > > +void __put_mtd_device(struct mtd_info *mtd) > > +{ > > + --mtd->usecount; > > + BUG_ON(mtd->usecount < 0); > > + > > if (mtd->put_device) > > mtd->put_device(mtd); > > > > module_put(mtd->owner); > > } > > That's racy, use kref. > Couldn't agree with you more.
However, these functions aren't intended for general use, and probably will be used by mtd translation layer only. I do have a lock that protects concurrent use of these functions.
Thus, I better add a comment about this?
Best regards, Maxim Levitsky
| |