Setting ->owner as done currently (pde->owner = THIS_MODULE) is racy
as correctly noted at bug #12454. Someone can lookup entry with NULL
->owner, thus not pinning enything, and release it later resulting
in module refcount underflow.
We can keep ->owner and supply it at registration time like ->proc_fops
and ->data.
But this leaves ->owner as easy-manipulative field (just one C assignment)
and somebody will forget to unpin previous/pin current module when
switching ->owner. ->proc_fops is declared as "const" which should give
some thoughts.
->read_proc/->write_proc were just fixed to not require ->owner for
protection.
rmmod'ed directories will be empty and return "." and ".." -- no harm.
And directories with tricky enough readdir and lookup shouldn't be modular.
We definitely don't want such modular code.
Removing ->owner will also make PDE smaller.
So, let's nuke it.
Kudos to Jeff Layton for reminding about this, let's say, oversight.
http://bugzilla.kernel.org/show_bug.cgi?id=12454
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
CC [M] arch/sparc/kernel/led.o
arch/sparc/kernel/led.c: In function 'led_blink':
arch/sparc/kernel/led.c:35: error: invalid use of undefined type 'struct
timer_list'
arch/sparc/kernel/led.c:35: error: 'jiffies' undeclared (first use in
this function)
arch/sparc/kernel/led.c:35: error: (Each undeclared identifier is
reported only once
arch/sparc/kernel/led.c:35: error: for each function it appears in.)
arch/sparc/kernel/led.c:36: error: 'avenrun' undeclared (first use in
this function)
arch/sparc/kernel/led.c:36: error: 'FSHIFT' undeclared (first use in
this function)
arch/sparc/kernel/led.c:36: error: 'HZ' undeclared (first use in this
function)
arch/sparc/kernel/led.c:37: error: invalid use of undefined type 'struct
timer_list'
arch/sparc/kernel/led.c:39: error: invalid use of undefined type 'struct
timer_list'
arch/sparc/kernel/led.c:40: error: invalid use of undefined type 'struct
timer_list'
arch/sparc/kernel/led.c:42: error: implicit declaration of function
'add_timer'
arch/sparc/kernel/led.c: In function 'led_write_proc':
arch/sparc/kernel/led.c:70: error: implicit declaration of function
'copy_from_user'
arch/sparc/kernel/led.c:84: error: implicit declaration of function
'del_timer_sync'
arch/sparc/kernel/led.c: In function 'led_init':
arch/sparc/kernel/led.c:109: error: implicit declaration of function
'init_timer'
arch/sparc/kernel/led.c:110: error: invalid use of undefined type
'struct timer_list'
make[1]: *** [arch/sparc/kernel/led.o] Error 1
Based upon original patch by Robert Reif.
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a forward port of a 2.4.x sun4m LED driver written by Lars
Kotthoff.
Signed-off-by: Lars Kotthoff <metalhead@metalhead.ws>
Signed-off-by: David S. Miller <davem@davemloft.net>
Alexey Dobriyan