Messages in this thread Patch in this message | | | From | Andres Salomon <> | Subject | Re: 2.6.33-rc1: WARNING: at kernel/mutex-debug.c:78 (geode hw rng?) | Date | Tue, 29 Dec 2009 18:22:01 -0500 |
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On Sun, 20 Dec 2009 01:44:56 +0100 Arnd Hannemann <hannemann@nets.rwth-aachen.de> wrote:
> Hi, > > not so sure if it is geode related. > While starting rngd on 2.6.33-rc1 on a geode machine, I got this > warning: > > [ 19.545852] ------------[ cut here ]------------ > [ 19.547554] WARNING: at kernel/mutex-debug.c:78 > debug_mutex_unlock+0x78/0xb8() > [ 19.547554] Modules linked in: ipt_LOG iptable_nat nf_nat > nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 arc4 ecb ath5k ehci_hcd > ohci_hcd mac80211 ath > [ 19.547554] Pid: 2509, comm: rngd Not tainted 2.6.33-rc1-ah0 #2 > [ 19.547554] Call Trace: > [ 19.547554] [<c102d86c>] ? debug_mutex_unlock+0x78/0xb8 > [ 19.547554] [<c10168bd>] warn_slowpath_common+0x60/0x77 > [ 19.547554] [<c10168e1>] warn_slowpath_null+0xd/0x10 > [ 19.547554] [<c102d86c>] debug_mutex_unlock+0x78/0xb8 > [ 19.547554] [<c1273314>] __mutex_unlock_slowpath+0x7b/0xa3 > [ 19.547554] [<c1273344>] mutex_unlock+0x8/0xa > [ 19.547554] [<c116de8c>] rng_dev_read+0x13b/0x156 > [ 19.547554] [<c116dd51>] ? rng_dev_read+0x0/0x156 > [ 19.547554] [<c105ac23>] vfs_read+0x8a/0x11a > [ 19.547554] [<c105af18>] sys_read+0x3b/0x60 > [ 19.547554] [<c127426d>] syscall_call+0x7/0xb > [ 19.547554] ---[ end trace cd1825d2e719f82e ]--- > > however, the system seems stable, and the hwrng seems to work fine... > > Best regards, > Arnd
Hm, I suspect that 9996508b is the culprit. Does the following patch help?
Subject: [PATCH] hw_random: don't attempt to unlock mutex twice
Commit 9996508b reworked rng_dev_read such that we unlock rng_mutex after exiting the loop; however, we also unlock it inside the loop before exiting. The out_unlock label should only be reached manually.
This code is starting to reach goto-considered-harmful territory. :/
Signed-off-by: Andres Salomon <dilinger@collabora.co.uk> --- drivers/char/hw_random/core.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index e989f67..29a5f6a 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -157,6 +157,9 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, err = -ERESTARTSYS; goto out; } + + if (!size) + goto out; } out_unlock: mutex_unlock(&rng_mutex); -- 1.5.6.5
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