Dear Sir
I found a bug about UBI, the specific problem is as follows： When ubi is attaching in function ubi_attach(), int ubi_attach(struct ubi_device *ubi, int force_scan) { … err = ubi_read_volume_table(ubi, ai); if (err) goto out_ai;
err = ubi_wl_init(ubi, ai); if (err) goto out_vtbl;
err = ubi_eba_init(ubi, ai); if (err) goto out_wl; … } it gonna call ubi wl init() and then call ubi eba init(), and on ubi_wl_init(), ensure_wear_leveling() was called immediately.
static int ensure_wear_leveling(struct ubi_device *ubi, int nested) { … if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) goto out_unlock; dbg_wl("schedule wear-leveling"); … if (nested) __schedule_ubi_work(ubi, wrk); else schedule_ubi_work(ubi, wrk); return err; … }
If e2->ec - e1->ec >= UBI_WL_THRESHOLD， schedule_ubi_work(ubi, wrk) was call immediately，and gonna call err = wrk->func(ubi, wrk, 0); wrk->func = &wear_leveling_worker，soon ubi_eba_copy_leb() was called.
int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to, struct ubi_vid_hdr *vid_hdr) { … err = leb_write_trylock(ubi, vol_id, lnum); if (err) { dbg_wl("contention on LEB %d:%d, cancel", vol_id, lnum); return MOVE_RETRY; }
/* * The LEB might have been put meanwhile, and the task which put it is * probably waiting on @ubi->move_mutex. No need to continue the work, * cancel it. */ if (vol->eba_tbl[lnum] != from) { dbg_wl("LEB %d:%d is no longer mapped to PEB %d, mapped to PEB %d, cancel", vol_id, lnum, from, vol->eba_tbl[lnum]); err = MOVE_CANCEL_RACE; goto out_unlock_leb; } … } At this place vol->eba_tbl[lnum] was access, but vol->eba_tbl actually need to wait until ubi_eba_init(ubi, ai) was called, so at this point, vol->eba_tbl is NULL point so bug on here.
Thanks
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