Messages in this thread Patch in this message | | | Date | Fri, 15 Oct 2021 08:55:11 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH 1/3] mtd: core: protect access to MTD devices while in suspend |
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On Mon, 11 Oct 2021 13:52:51 +0200 Sean Nyekjaer <sean@geanix.com> wrote:
> struct mtd_info { > @@ -476,10 +478,49 @@ static inline u32 mtd_oobavail(struct mtd_info *mtd, struct mtd_oob_ops *ops) > return ops->mode == MTD_OPS_AUTO_OOB ? mtd->oobavail : mtd->oobsize; > } > > +static inline void mtd_start_access(struct mtd_info *mtd) > +{ > + struct mtd_info *master = mtd_get_master(mtd);
mtd_start_{access,end}() should only be called on master devices, so I guess you can drop the mtd_get_master() call and use mtd directly. Maybe add a WARN_ON_ONCE(mtd != mtd_get_master(mtd)) so we can easily catch silly mistakes.
> + > + /* > + * Don't take the suspend_lock on devices that don't > + * implement the suspend hook. Otherwise, lockdep will > + * complain about nested locks when trying to suspend MTD > + * partitions or MTD devices created by gluebi which are > + * backed by real devices. > + */ > + if (!master->_suspend) > + return; > + > + /* > + * Wait until the device is resumed. Should we have a > + * non-blocking mode here? > + */ > + while (1) { > + down_read(&master->master.suspend_lock); > + if (!master->master.suspended) > + return; > + > + up_read(&master->master.suspend_lock); > + wait_event(master->master.resume_wq, master->master.suspended == 0); > + } > +} > + > +static inline void mtd_end_access(struct mtd_info *mtd) > +{ > + struct mtd_info *master = mtd_get_master(mtd); > + > + if (!master->_suspend) > + return; > + > + up_read(&master->master.suspend_lock); > +} > + > static inline int mtd_max_bad_blocks(struct mtd_info *mtd, > loff_t ofs, size_t len) > { > struct mtd_info *master = mtd_get_master(mtd); > + int ret; > > if (!master->_max_bad_blocks) > return -ENOTSUPP; > @@ -487,8 +528,12 @@ static inline int mtd_max_bad_blocks(struct mtd_info *mtd, > if (mtd->size < (len + ofs) || ofs < 0) > return -EINVAL; > > - return master->_max_bad_blocks(master, mtd_get_master_ofs(mtd, ofs), > - len); > + mtd_start_access(mtd); > + ret = master->_max_bad_blocks(master, mtd_get_master_ofs(mtd, ofs), > + len); > + mtd_end_access(mtd);
Please pass the master to those functions, there's no point walking the parent chain again in the start/end_access() functions if you already have the master retrieved in the caller. Oh, and there seems to be a common pattern here, so maybe it's worth adding those macros:
#define mtd_no_suspend_void_call(master, method, ...) \ mtd_start_access(master); \ master->method(master, __VA_ARGS__); \ mtd_end_access(master);
#define mtd_no_suspend_ret_call(ret, master, method, ...) \ mtd_start_access(master); \ ret = master->method(master, __VA_ARGS__); \ mtd_end_access(master);
I don't really like the helper names, so feel free to propose something else.
> + > + return ret; > } >
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