hi, Jiri
This warning should blame on commit 5a640967 ("tty/n_gsm.c: fix a memory leak in gsmld_open()"). When gsm driver failed to activate one mux,there is memory leak. So I call this ->cleanup() to do the cleanup work. Seems I did not consider all cases.
I have one confusion. As there is field gsm->num to store the index of gsm_mux[]. so in gsm_cleanup_mux(), why we still use for-loop to find this mux?
In error handle path, for example, the call trace in this patch, as we failed to activate it and the
gsm->num is invalid(and the value is 0). we can just modify the codes like below:
if(gsm_mux[gsm->num] == gsm)
....other work
else
return;
I think it would work, and the logic is correct. Or I just miss something important?
thanks
xinhui
On 2015/11/25 00:54, Jiri Slaby wrote:
Dmitry reported, that the current cleanup code in n_gsm can trigger a
warning:
WARNING: CPU: 2 PID: 24238 at drivers/tty/n_gsm.c:2048 gsm_cleanup_mux+0x166/0x6b0()
...
Call Trace:
...
[<ffffffff81247ab9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:490
[<ffffffff828d0456>] gsm_cleanup_mux+0x166/0x6b0 drivers/tty/n_gsm.c:2048
[<ffffffff828d4d87>] gsmld_open+0x5b7/0x7a0 drivers/tty/n_gsm.c:2386
[<ffffffff828b9078>] tty_ldisc_open.isra.2+0x78/0xd0 drivers/tty/tty_ldisc.c:447
[<ffffffff828b973a>] tty_set_ldisc+0x1ca/0xa70 drivers/tty/tty_ldisc.c:567
[< inline >] tiocsetd drivers/tty/tty_io.c:2650
[<ffffffff828a14ea>] tty_ioctl+0xb2a/0x2140 drivers/tty/tty_io.c:2883
...
But this is a legal path when open fails to find a space in the
gsm_mux array and tries to clean up. So make it a standard test
instead of a warning.
Reported-by: "Dmitry Vyukov" <dvyukov@xxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/CACT4Y+bHQbAB68VFi7Romcs-Z9ZW3kQRvcq+BvHH1oa5NcAdLA@xxxxxxxxxxxxxx
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/tty/n_gsm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index c3fe026d3168..9aff37186246 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2045,7 +2045,9 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm)
}
}
spin_unlock(&gsm_mux_lock);
- WARN_ON(i == MAX_MUX);
+ /* open failed before registering => nothing to do */
+ if (i == MAX_MUX)
+ return;
/* In theory disconnecting DLCI 0 is sufficient but for some
modems this is apparently not the case. */
--
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