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    SubjectRe: [ANNOUNCE] 2.6.33.1-rt11 - BUG?
    On Thu, 1 Apr 2010, Xianghua Xiao wrote:

    > I'm testing 2.6.33.1 on ppc 834x with rt11 patch. After system is up I keep
    > seeing this same message from dmesg:
    >
    > BUG: sleeping function called from invalid context at kernel/rtmutex.c:684
    > pcnt: 0 0 in_atomic(): 0, irqs_disabled(): 1, pid: 16, name: events/0
    > Call Trace:
    > [cf85be80] [c00096cc] show_stack+0x6c/0x1a4 (unreliable)
    > [cf85beb0] [c001f928] __might_sleep+0x104/0x108
    > [cf85bec0] [c03cb444] rt_spin_lock+0xa0/0xa4
    > [cf85bed0] [c0270b6c] lock_tx_qs+0x40/0x68
    > [cf85bef0] [c02712cc] adjust_link+0x4c/0x240
    > [cf85bf20] [c026d5ec] phy_state_machine+0x3bc/0x628
    > [cf85bf40] [c003e69c] worker_thread+0x148/0x1f0
    > [cf85bfa0] [c0042ec0] kthread+0x84/0x88
    > [cf85bff0] [c00137f8] kernel_thread+0x4c/0x68
    > BUG: sleeping function called from invalid context at kernel/rtmutex.c:684
    > pcnt: 0 0 in_atomic(): 0, irqs_disabled(): 1, pid: 16, name: events/0
    >
    > #uname -a
    > Linux 2.6.33.1-rt11 #3 PREEMPT RT Thu Apr 1 11:58:25 CDT 2010 ppc unknown
    >
    > This does not hang/lock the system yet...google reported similar 'bug' on
    > older kernels. Is this a bug from 2.6.33.1-rt11 patch or I have to change
    > phy.c somehow to avoid it? This traces back to a mutex lock in phy.c.

    No, it traces back to a call to lock_tx_qs() which is a spinlock in
    mainline and gets converted to a "sleeping" spinlock in -RT. That
    means it can't be called with interrupts disabled. But the code in
    adjust_link does exaclty that.

    Does the patch below fix it ?

    Thanks,

    tglx
    ---
    Subject: net-gianfar-fix-rt-splat.patch
    From: Thomas Gleixner <tglx@linutronix.de>
    Date: Thu, 01 Apr 2010 20:20:57 +0200

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    drivers/net/gianfar.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    Index: linux-2.6-tip/drivers/net/gianfar.c
    ===================================================================
    --- linux-2.6-tip.orig/drivers/net/gianfar.c
    +++ linux-2.6-tip/drivers/net/gianfar.c
    @@ -2717,7 +2717,7 @@ static void adjust_link(struct net_devic
    struct phy_device *phydev = priv->phydev;
    int new_state = 0;

    - local_irq_save(flags);
    + local_irq_save_nort(flags);
    lock_tx_qs(priv);

    if (phydev->link) {
    @@ -2785,7 +2785,7 @@ static void adjust_link(struct net_devic
    if (new_state && netif_msg_link(priv))
    phy_print_status(phydev);
    unlock_tx_qs(priv);
    - local_irq_restore(flags);
    + local_irq_restore_nort(flags);
    }

    /* Update the hash table based on the current list of multicast





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