Hi Arnd： If we can get list_add(&misc->list, &misc_list), then there is no problem at all, but if the misc_register return "-EBUSY"(Maybe the same miscdevice register twice ), then the deadloop will happen at list_for_each_entry(c, &misc_list, list); So at my opinion just remove the initialization code or do initialization when we need do list_add.
-----Original Message----- From: arndbergm...@gmail.com [mailto:arndbergm...@gmail.com] On Behalf Of Arnd Bergmann Sent: Monday, June 26, 2017 6:03 PM To: Orson Zhai (翟京) Cc: Greg Kroah-Hartman; Linux Kernel Mailing List; Zhongping Tan (谭中平) Subject: Re: [RFC PATCH] char: misc: Init misc->list in a safe way On Mon, Jun 26, 2017 at 11:31 AM, Orson Zhai <orson.z...@spreadtrum.com> wrote: > From: Zhongping Tan <zhongping....@spreadtrum.com> > > It is likely to enter a wrong case and return an error when > registerring a misc device. As a result, misc->list will be intialized > to a dead loop which is possible to go into wrong situation if anyone > refers to it else where. > > Move the initializion line out of all error branches to avoid any side > effect. > > Signed-off-by: Zhongping Tan <zhongping....@spreadtrum.com> > Signed-off-by: Orson Zhai <orson.z...@spreadtrum.com> I fail to see the problem. Did you run into a bug that gets fixed by this patch, or did you arrive here after code inspection? As far as I can tell, the INIT_LIST_HEAD() on the entry has no effect at all, the fields simply get initialized in the list_add(), and the list traversal is protected using misc_mtx. Arnd
