Return-Path: Date: Thu, 20 Mar 2014 14:03:57 -0500 From: Felipe Balbi To: Felipe Balbi CC: Peter Hurley , Marcel Holtmann , Alan Cox , Greg KH , Muralidharan Karicheri , , , Linux Kernel Mailing List , Huang Shijie Subject: Re: hci_ldsic nested locking problem Message-ID: <20140320190357.GG3959@saruman.home> Reply-To: References: <20140320163435.GH32692@saruman.home> <1395333736.22077.32.camel@acox1-desk.ger.corp.intel.com> <20140320171621.GA2827@saruman.home> <532B25FC.3070408@hurleysoftware.com> <20140320181145.GC3959@saruman.home> <532B319D.4090208@hurleysoftware.com> <20140320182528.GE3959@saruman.home> <20140320190154.GF3959@saruman.home> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Fnm8lRGFTVS/3GuM" In-Reply-To: <20140320190154.GF3959@saruman.home> List-ID: --Fnm8lRGFTVS/3GuM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, Mar 20, 2014 at 02:01:54PM -0500, Felipe Balbi wrote: > > @@ -318,6 +326,8 @@ static void hci_uart_tty_close(struct tty_struct *t= ty) > > if (hdev) > > hci_uart_close(hdev); > > =20 > > + cancel_work_sync(&hy->write_work); >=20 > forgot to commit, darn it here it is: =46rom eaf7ff6f2d224f202369e4820b76a03fa664fab0 Mon Sep 17 00:00:00 2001 =46rom: Felipe Balbi Date: Thu, 20 Mar 2014 13:20:10 -0500 Subject: [PATCH] bluetooth: hci_ldisc: fix deadlock condition LDISCs shouldn't call tty->ops->write() from within ->write_wakeup(). ->write_wakeup() is called with port lock taken and IRQs disabled, tty->ops->write() will try to acquire the same port lock and we will deadlock. Signed-off-by: Felipe Balbi --- drivers/bluetooth/hci_ldisc.c | 20 +++++++++++++++----- drivers/bluetooth/hci_uart.h | 1 + 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index 6e06f6f..5a53e50 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -118,10 +118,6 @@ static inline struct sk_buff *hci_uart_dequeue(struct = hci_uart *hu) =20 int hci_uart_tx_wakeup(struct hci_uart *hu) { - struct tty_struct *tty =3D hu->tty; - struct hci_dev *hdev =3D hu->hdev; - struct sk_buff *skb; - if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) { set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); return 0; @@ -129,6 +125,18 @@ int hci_uart_tx_wakeup(struct hci_uart *hu) =20 BT_DBG(""); =20 + schedule_work(&hu->write_work); + + return 0; +} + +static void hci_uart_write_work(struct work_struct *work) +{ + struct hci_uart *hu =3D container_of(work, struct hci_uart, init_ready); + struct tty_struct *tty =3D hu->tty; + struct hci_dev *hdev =3D hu->hdev; + struct sk_buff *skb; + restart: clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); =20 @@ -153,7 +161,6 @@ restart: goto restart; =20 clear_bit(HCI_UART_SENDING, &hu->tx_state); - return 0; } =20 static void hci_uart_init_work(struct work_struct *work) @@ -281,6 +288,7 @@ static int hci_uart_tty_open(struct tty_struct *tty) tty->receive_room =3D 65536; =20 INIT_WORK(&hu->init_ready, hci_uart_init_work); + INIT_WORK(&hu->write_work, hci_uart_write_work); =20 spin_lock_init(&hu->rx_lock); =20 @@ -318,6 +326,8 @@ static void hci_uart_tty_close(struct tty_struct *tty) if (hdev) hci_uart_close(hdev); =20 + cancel_work_sync(&hu->write_work); + if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) { if (hdev) { if (test_bit(HCI_UART_REGISTERED, &hu->flags)) diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h index fffa61f..12df101 100644 --- a/drivers/bluetooth/hci_uart.h +++ b/drivers/bluetooth/hci_uart.h @@ -68,6 +68,7 @@ struct hci_uart { unsigned long hdev_flags; =20 struct work_struct init_ready; + struct work_struct write_work; =20 struct hci_uart_proto *proto; void *priv; --=20 1.9.1.286.g5172cb3 --=20 balbi --Fnm8lRGFTVS/3GuM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJTKzudAAoJEIaOsuA1yqRE4cwP/3pUTISIhQVOzyYIwCwwIEw/ lWxnQjhaGuoYYlL1sFoAucj0vh9AHDH3zE74/ltSoBR5GT+mx2HxvrYmTRCpMVD8 pD0bcRnVWx5j3tJbDVZVC/DuiL06TTTn/MRVcs36U4CRtXF2hurBqx3mAtalt1FO MzTf7pH6wpUEFEbnqnOY3lrfKrtATn8fP/GXSIcnButY3z4C/FiAwsDqOTdKb0+J zmVsdeRYv8HDMfOuLuNEttFcBIOMMW5p1UEvYmSksr1VNtEhm1pL7E7mGPW69Mr2 VoSMkeSAyJosNs+4TCcvWkuOJrZjZTeTibf96C3uhILFM+sJOP9O+rCHRaveBphM Q5+0FmZ6bSC+/ZGhWQAeQjG0NocoSL6KEpMirABLhDQmvCyt+PBYLH6ztrV8wyZD 0eFqqIqGiCnQL1rWgzNMlWCdqiBefc5trBAbTElTPcfOYRV3GnnUyi/CRV5WExg8 zLPm5NaslZdD7/TCX6h2F4zkiTQe6LV3s7u6NPA8g1L8BNhqX/3Vs28ePi90Lluj qEe4SvO1fa5261EsipfmdRj6YzjIVE24TZY5SCUrpEWuCpaWAPPOUK3lb5+b7D2q HbvFsfTmIhsGefHqP5SoC3UfLrous67B7PZOovYLYDNQ64WZuF4+JwdZVuv8XaY0 M2KFvQMahyVBnz19sgIi =sTPQ -----END PGP SIGNATURE----- --Fnm8lRGFTVS/3GuM--