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Date: Mon, 04 Aug 2008 15:41:30 +1000
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Cc: linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
Mariusz Kozlowski <m.kozlowski@...land.pl>,
FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
Borislav Petkov <petkovbb@...il.com>
Subject: Re: [PATCH] ide: fix regression caused by ide_device_{get,put}()
addition (take 2)
On Sun, 2008-08-03 at 16:48 +0200, Bartlomiej Zolnierkiewicz wrote:
> Ben, please use this version instead
> (together with ide_host_alloc_all() fix)
> for media-bay testing.
>
> From: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> Subject: [PATCH] ide: fix regression caused by ide_device_{get,put}() addition (take 2)
What is the ide_host_alloc_all() fix ?
Ben.
> On Monday 28 July 2008, Benjamin Herrenschmidt wrote:
>
> [...]
>
> > Vector: 300 (Data Access) at [c58b7b80]
> > pc: c014f264: elv_may_queue+0x10/0x44
> > lr: c0152750: get_request+0x2c/0x2c0
> > sp: c58b7c30
> > msr: 1032
> > dar: c
> > dsisr: 40000000
> > current = 0xc58aaae0
> > pid = 854, comm = media-bay
> > enter ? for help
> > mon> t
> > [c58b7c40] c0152750 get_request+0x2c/0x2c0
> > [c58b7c70] c0152a08 get_request_wait+0x24/0xec
> > [c58b7cc0] c0225674 ide_cd_queue_pc+0x58/0x1a0
> > [c58b7d40] c022672c ide_cdrom_packet+0x9c/0xdc
> > [c58b7d70] c0261810 cdrom_get_disc_info+0x60/0xd0
> > [c58b7dc0] c026208c cdrom_mrw_exit+0x1c/0x11c
> > [c58b7e30] c0260f7c unregister_cdrom+0x84/0xe8
> > [c58b7e50] c022395c ide_cd_release+0x80/0x84
> > [c58b7e70] c0163650 kref_put+0x54/0x6c
> > [c58b7e80] c0223884 ide_cd_put+0x40/0x5c
> > [c58b7ea0] c0211100 generic_ide_remove+0x28/0x3c
> > [c58b7eb0] c01e9d34 __device_release_driver+0x78/0xb4
> > [c58b7ec0] c01e9e44 device_release_driver+0x28/0x44
> > [c58b7ee0] c01e8f7c bus_remove_device+0xac/0xd8
> > [c58b7f00] c01e7424 device_del+0x104/0x198
> > [c58b7f20] c01e74d0 device_unregister+0x18/0x30
> > [c58b7f40] c02121c4 __ide_port_unregister_devices+0x6c/0x88
> > [c58b7f60] c0212398 ide_port_unregister_devices+0x38/0x80
> > [c58b7f80] c0208ca4 media_bay_step+0x1cc/0x5c0
> > [c58b7fb0] c0209124 media_bay_task+0x8c/0xcc
> > [c58b7fd0] c00485c0 kthread+0x48/0x84
> > [c58b7ff0] c0011b20 kernel_thread+0x44/0x60
>
> The guilty commit turned out to be 08da591e14cf87247ec09b17c350235157a92fc3
> ("ide: add ide_device_{get,put}() helpers"). ide_device_put() is called
> before kref_put() in ide_cd_put() so IDE device is already gone by the time
> ide_cd_release() is reached.
>
> Fix it by calling ide_device_get() before kref_get() and ide_device_put()
> after kref_put() in all affected device drivers.
>
> v2:
> Brown paper bag time. In v1 cd->drive was referenced after dropping last
> reference on cd object (which could result in OOPS in ide_device_put() as
> reported/debugged by Mariusz Kozlowski). Fix it by caching cd->drive in
> the local variable (fix other device drivers too).
>
> Reported-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Reported-by: Mariusz Kozlowski <m.kozlowski@...land.pl>
> Cc: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> Cc: Borislav Petkov <petkovbb@...il.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
> ---
> replacement patch
>
> drivers/ide/ide-cd.c | 12 +++++++-----
> drivers/ide/ide-disk.c | 11 ++++++-----
> drivers/ide/ide-floppy.c | 11 ++++++-----
> drivers/ide/ide-tape.c | 11 ++++++-----
> drivers/scsi/ide-scsi.c | 11 ++++++-----
> 5 files changed, 31 insertions(+), 25 deletions(-)
>
> Index: b/drivers/ide/ide-cd.c
> ===================================================================
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -66,11 +66,11 @@ static struct cdrom_info *ide_cd_get(str
> mutex_lock(&idecd_ref_mutex);
> cd = ide_cd_g(disk);
> if (cd) {
> - kref_get(&cd->kref);
> - if (ide_device_get(cd->drive)) {
> - kref_put(&cd->kref, ide_cd_release);
> + if (ide_device_get(cd->drive))
> cd = NULL;
> - }
> + else
> + kref_get(&cd->kref);
> +
> }
> mutex_unlock(&idecd_ref_mutex);
> return cd;
> @@ -78,9 +78,11 @@ static struct cdrom_info *ide_cd_get(str
>
> static void ide_cd_put(struct cdrom_info *cd)
> {
> + ide_drive_t *drive = cd->drive;
> +
> mutex_lock(&idecd_ref_mutex);
> - ide_device_put(cd->drive);
> kref_put(&cd->kref, ide_cd_release);
> + ide_device_put(drive);
> mutex_unlock(&idecd_ref_mutex);
> }
>
> Index: b/drivers/ide/ide-disk.c
> ===================================================================
> --- a/drivers/ide/ide-disk.c
> +++ b/drivers/ide/ide-disk.c
> @@ -63,11 +63,10 @@ static struct ide_disk_obj *ide_disk_get
> mutex_lock(&idedisk_ref_mutex);
> idkp = ide_disk_g(disk);
> if (idkp) {
> - kref_get(&idkp->kref);
> - if (ide_device_get(idkp->drive)) {
> - kref_put(&idkp->kref, ide_disk_release);
> + if (ide_device_get(idkp->drive))
> idkp = NULL;
> - }
> + else
> + kref_get(&idkp->kref);
> }
> mutex_unlock(&idedisk_ref_mutex);
> return idkp;
> @@ -75,9 +74,11 @@ static struct ide_disk_obj *ide_disk_get
>
> static void ide_disk_put(struct ide_disk_obj *idkp)
> {
> + ide_drive_t *drive = idkp->drive;
> +
> mutex_lock(&idedisk_ref_mutex);
> - ide_device_put(idkp->drive);
> kref_put(&idkp->kref, ide_disk_release);
> + ide_device_put(drive);
> mutex_unlock(&idedisk_ref_mutex);
> }
>
> Index: b/drivers/ide/ide-floppy.c
> ===================================================================
> --- a/drivers/ide/ide-floppy.c
> +++ b/drivers/ide/ide-floppy.c
> @@ -168,11 +168,10 @@ static struct ide_floppy_obj *ide_floppy
> mutex_lock(&idefloppy_ref_mutex);
> floppy = ide_floppy_g(disk);
> if (floppy) {
> - kref_get(&floppy->kref);
> - if (ide_device_get(floppy->drive)) {
> - kref_put(&floppy->kref, idefloppy_cleanup_obj);
> + if (ide_device_get(floppy->drive))
> floppy = NULL;
> - }
> + else
> + kref_get(&floppy->kref);
> }
> mutex_unlock(&idefloppy_ref_mutex);
> return floppy;
> @@ -180,9 +179,11 @@ static struct ide_floppy_obj *ide_floppy
>
> static void ide_floppy_put(struct ide_floppy_obj *floppy)
> {
> + ide_drive_t *drive = floppy->drive;
> +
> mutex_lock(&idefloppy_ref_mutex);
> - ide_device_put(floppy->drive);
> kref_put(&floppy->kref, idefloppy_cleanup_obj);
> + ide_device_put(drive);
> mutex_unlock(&idefloppy_ref_mutex);
> }
>
> Index: b/drivers/ide/ide-tape.c
> ===================================================================
> --- a/drivers/ide/ide-tape.c
> +++ b/drivers/ide/ide-tape.c
> @@ -331,11 +331,10 @@ static struct ide_tape_obj *ide_tape_get
> mutex_lock(&idetape_ref_mutex);
> tape = ide_tape_g(disk);
> if (tape) {
> - kref_get(&tape->kref);
> - if (ide_device_get(tape->drive)) {
> - kref_put(&tape->kref, ide_tape_release);
> + if (ide_device_get(tape->drive))
> tape = NULL;
> - }
> + else
> + kref_get(&tape->kref);
> }
> mutex_unlock(&idetape_ref_mutex);
> return tape;
> @@ -343,9 +342,11 @@ static struct ide_tape_obj *ide_tape_get
>
> static void ide_tape_put(struct ide_tape_obj *tape)
> {
> + ide_drive_t *drive = tape->drive;
> +
> mutex_lock(&idetape_ref_mutex);
> - ide_device_put(tape->drive);
> kref_put(&tape->kref, ide_tape_release);
> + ide_device_put(drive);
> mutex_unlock(&idetape_ref_mutex);
> }
>
> Index: b/drivers/scsi/ide-scsi.c
> ===================================================================
> --- a/drivers/scsi/ide-scsi.c
> +++ b/drivers/scsi/ide-scsi.c
> @@ -101,11 +101,10 @@ static struct ide_scsi_obj *ide_scsi_get
> mutex_lock(&idescsi_ref_mutex);
> scsi = ide_scsi_g(disk);
> if (scsi) {
> - scsi_host_get(scsi->host);
> - if (ide_device_get(scsi->drive)) {
> - scsi_host_put(scsi->host);
> + if (ide_device_get(scsi->drive))
> scsi = NULL;
> - }
> + else
> + scsi_host_get(scsi->host);
> }
> mutex_unlock(&idescsi_ref_mutex);
> return scsi;
> @@ -113,9 +112,11 @@ static struct ide_scsi_obj *ide_scsi_get
>
> static void ide_scsi_put(struct ide_scsi_obj *scsi)
> {
> + ide_drive_t *drive = scsi->drive;
> +
> mutex_lock(&idescsi_ref_mutex);
> - ide_device_put(scsi->drive);
> scsi_host_put(scsi->host);
> + ide_device_put(drive);
> mutex_unlock(&idescsi_ref_mutex);
> }
>
> --
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