From: Greg Kroah-Hartman gregkh@linuxfoundation.org
commit c7084edc3f6d67750f50d4183134c4fb5712a5c8 upstream.
The n_r3964 line discipline driver was written in a different time, when SMP machines were rare, and users were trusted to do the right thing. Since then, the world has moved on but not this code, it has stayed rooted in the past with its lovely hand-crafted list structures and loads of "interesting" race conditions all over the place.
After attempting to clean up most of the issues, I just gave up and am now marking the driver as BROKEN so that hopefully someone who has this hardware will show up out of the woodwork (I know you are out there!) and will help with debugging a raft of changes that I had laying around for the code, but was too afraid to commit as odds are they would break things.
Many thanks to Jann and Linus for pointing out the initial problems in this codebase, as well as many reviews of my attempts to fix the issues. It was a case of whack-a-mole, and as you can see, the mole won.
Reported-by: Jann Horn jannh@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
--- drivers/char/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -377,7 +377,7 @@ config XILINX_HWICAP
config R3964 tristate "Siemens R3964 line discipline" - depends on TTY + depends on TTY && BROKEN ---help--- This driver allows synchronous communication with devices using the Siemens R3964 packet protocol. Unless you are dealing with special