From: Peter Zijlstra <peterz@infradead.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@redhat.com>,
USB list <linux-usb@vger.kernel.org>,
Kernel development list <linux-kernel@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>
Subject: Re: Memory barrier needed with wake_up_process()?
Date: Tue, 6 Sep 2016 17:05:47 +0200 [thread overview]
Message-ID: <20160906150547.GG2794@worktop> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1609061043420.1951-100000@iolanthe.rowland.org>
On Tue, Sep 06, 2016 at 10:46:55AM -0400, Alan Stern wrote:
Not knowing where INFO() goes, you should use trace_printk() not
printk(), as the former is strictly per cpu, while the latter is
globally serialized and can hide all these problems.
> Index: usb-4.x/drivers/usb/gadget/function/f_mass_storage.c
> ===================================================================
> --- usb-4.x.orig/drivers/usb/gadget/function/f_mass_storage.c
> +++ usb-4.x/drivers/usb/gadget/function/f_mass_storage.c
> @@ -485,6 +485,8 @@ static void bulk_out_complete(struct usb
> spin_lock(&common->lock);
> bh->outreq_busy = 0;
> bh->state = BUF_STATE_FULL;
> + if (bh->bulk_out_intended_length == US_BULK_CB_WRAP_LEN)
> + INFO(common, "compl: bh %p state %d\n", bh, bh->state);
> wakeup_thread(common);
> spin_unlock(&common->lock);
> }
> @@ -2207,6 +2209,7 @@ static int get_next_command(struct fsg_c
> rc = sleep_thread(common, true);
> if (rc)
> return rc;
> + INFO(common, "next: bh %p state %d\n", bh, bh->state);
> }
> smp_rmb();
> rc = fsg_is_set(common) ? received_cbw(common->fsg, bh) : -EIO;
>
next prev parent reply other threads:[~2016-09-06 15:06 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-02 18:10 Memory barrier needed with wake_up_process()? Alan Stern
2016-09-02 18:47 ` Paul E. McKenney
2016-09-02 20:29 ` Alan Stern
2016-09-03 9:07 ` Paul E. McKenney
2016-09-03 12:31 ` Peter Zijlstra
2016-09-03 14:26 ` Alan Stern
2016-09-03 14:49 ` Alan Stern
2016-09-05 8:33 ` Peter Zijlstra
2016-09-05 15:29 ` Alan Stern
2016-09-06 11:36 ` Peter Zijlstra
2016-09-06 11:43 ` Felipe Balbi
2016-09-06 11:49 ` Peter Zijlstra
2016-09-06 12:20 ` Peter Zijlstra
2016-09-06 14:46 ` Alan Stern
2016-09-06 15:05 ` Peter Zijlstra [this message]
2016-09-07 10:12 ` Felipe Balbi
2016-09-09 10:36 ` Felipe Balbi
2016-09-09 16:12 ` Alan Stern
2016-09-19 11:11 ` Felipe Balbi
2016-09-19 17:35 ` Alan Stern
2016-09-20 10:12 ` Felipe Balbi
2016-09-20 12:53 ` Felipe Balbi
2016-09-20 14:40 ` Alan Stern
2017-01-16 11:12 ` Felipe Balbi
2017-01-16 17:09 ` Alan Stern
2017-01-16 19:04 ` Felipe Balbi
2017-01-16 19:19 ` Felipe Balbi
2016-09-02 19:18 ` Peter Zijlstra
2016-09-02 20:16 ` Alan Stern
2016-09-02 22:14 ` Peter Zijlstra
2016-09-02 22:16 ` Peter Zijlstra
2016-09-05 9:43 ` Will Deacon
2016-09-06 11:10 ` Peter Zijlstra
2016-09-02 22:16 ` Peter Zijlstra
2016-09-03 6:58 ` Felipe Balbi
2016-09-03 12:19 ` Peter Zijlstra
2016-09-03 13:51 ` Felipe Balbi
2016-09-05 8:09 ` Peter Zijlstra
2016-09-03 14:16 ` Alan Stern
2016-09-05 8:08 ` Peter Zijlstra
2016-09-05 14:33 ` Alan Stern
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