Date: Sun, 21 Dec 2008 23:31:18 +0100 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> To: Ferner Cilloniz <fernercc@gmail.com> Cc: freebsd-hackers@freebsd.org, Julian Elischer <julian@elischer.org> Subject: Re: adding proc to allproc Message-ID: <86ocz55fex.fsf@ds4.des.no> In-Reply-To: <1229739800.5614.24.camel@mobiliare.Belkin> (Ferner Cilloniz's message of "Sat, 20 Dec 2008 02:23:20 %2B0000") References: <1229726360.5614.15.camel@mobiliare.Belkin> <494C8246.3020703@elischer.org> <1229729326.5614.16.camel@mobiliare.Belkin> <494C8508.2020000@elischer.org> <1229739800.5614.24.camel@mobiliare.Belkin>
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Ferner Cilloniz <fernercc@gmail.com> writes: > The process comes from the allproc list. > I am simply iterating through this list and removing the first 1/2 of > allproc list and adding the removed process to my own singly linked > list. > > LIST_REMOVE(current_proc, p_list); // remove from the allproc > add_proc_entry(current_proc); You can't do that without holding allproc_lock. > Later, i am iterating through my singly linked list and doing the below: > > struct proc *p =3D current->p; > f( p !=3D NULL && (p->p_state =3D=3D PRS_NEW || p->p_state =3D=3D PRS_NOR= MAL) ){ > LIST_INSERT_HEAD(&allproc, p, p_list); > } You can't do that without holding allproc_lock. > struct proc_ll *new_entry =3D (struct proc_ll*)malloc(sizeof(struct > proc_ll), M_TEMP, M_ZERO | M_NOWAIT); unnecessary cast, missing NULL check > int done =3D 0; unused variable > new_entry->p =3D p; // maybe doing this assignment isnt correct? > > if(proc_entries =3D=3D NULL) { > proc_entries =3D new_entry; > return; > } > > struct proc_ll *current =3D proc_entries; > > while(current !=3D NULL) { > if(current->next =3D=3D NULL) { > current->next =3D new_entry; > break; > } > current =3D current->next; > } This is gross. The usual idiom is new_entry->next =3D proc_entries; proc_entries =3D new_entry; However, the simplest solution is to use the <sys/queue.h> macros. > A circular list does sound like it could cause hanging to occur but the > above code, atleast from my eyes, doesn't seem to cause it. With no locking, who knows what really goes on in your code... DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no
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