* [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
@ 2015-09-16 16:52 Matthew R. Ochs
0 siblings, 0 replies; 6+ messages in thread
From: Matthew R. Ochs @ 2015-09-16 16:52 UTC (permalink / raw)
To: linux-scsi, James.Bottomley, nab, brking, imunsie, dja,
andrew.donnellan
Cc: mikey, linuxppc-dev, Manoj N. Kumar
When a LUN is removed, the sdev that is associated with the LUN
remains intact until its reference count drops to 0. In order
to prevent an sdev from being removed while a context is still
associated with it, obtain an additional reference per-context
for each LUN attached to the context.
This resolves a potential Oops in the release handler when a
dealing with a LUN that has already been removed.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Suggested-by: Brian King <brking@linux.vnet.ibm.com>
---
drivers/scsi/cxlflash/superpipe.c | 36 ++++++++++++++++++++++++------------
1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index fa513ba..1fa4af6 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -880,6 +880,9 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
sys_close(lfd);
}
+ /* Release the sdev reference that bound this LUN to the context */
+ scsi_device_put(sdev);
+
out:
if (put_ctx)
put_context(ctxi);
@@ -1287,11 +1290,18 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
}
}
+ rc = scsi_device_get(sdev);
+ if (unlikely(rc)) {
+ dev_err(dev, "%s: Unable to get sdev reference!\n", __func__);
+ goto out;
+ }
+
lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
if (unlikely(!lun_access)) {
dev_err(dev, "%s: Unable to allocate lun_access!\n", __func__);
+ scsi_device_put(sdev);
rc = -ENOMEM;
- goto out;
+ goto err0;
}
lun_access->lli = lli;
@@ -1311,21 +1321,21 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
dev_err(dev, "%s: Could not initialize context %p\n",
__func__, ctx);
rc = -ENODEV;
- goto err0;
+ goto err1;
}
ctxid = cxl_process_element(ctx);
if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
rc = -EPERM;
- goto err1;
+ goto err2;
}
file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
if (unlikely(fd < 0)) {
rc = -ENODEV;
dev_err(dev, "%s: Could not get file descriptor\n", __func__);
- goto err1;
+ goto err2;
}
/* Translate read/write O_* flags from fcntl.h to AFU permission bits */
@@ -1335,7 +1345,7 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
if (unlikely(!ctxi)) {
dev_err(dev, "%s: Failed to create context! (%d)\n",
__func__, ctxid);
- goto err2;
+ goto err3;
}
work = &ctxi->work;
@@ -1346,13 +1356,13 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
if (unlikely(rc)) {
dev_dbg(dev, "%s: Could not start context rc=%d\n",
__func__, rc);
- goto err3;
+ goto err4;
}
rc = afu_attach(cfg, ctxi);
if (unlikely(rc)) {
dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
- goto err4;
+ goto err5;
}
/*
@@ -1388,13 +1398,13 @@ out:
__func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
return rc;
-err4:
+err5:
cxl_stop_context(ctx);
-err3:
+err4:
put_context(ctxi);
destroy_context(cfg, ctxi);
ctxi = NULL;
-err2:
+err3:
/*
* Here, we're overriding the fops with a dummy all-NULL fops because
* fput() calls the release fop, which will cause us to mistakenly
@@ -1406,10 +1416,12 @@ err2:
fput(file);
put_unused_fd(fd);
fd = -1;
-err1:
+err2:
cxl_release_context(ctx);
-err0:
+err1:
kfree(lun_access);
+err0:
+ scsi_device_put(sdev);
goto out;
}
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
2015-09-16 21:23 [PATCH v2 00/30] cxlflash: Miscellaneous bug fixes and corrections Matthew R. Ochs
@ 2015-09-16 21:27 ` Matthew R. Ochs
2015-09-18 1:26 ` Brian King
2015-09-21 12:11 ` Tomas Henzl
0 siblings, 2 replies; 6+ messages in thread
From: Matthew R. Ochs @ 2015-09-16 21:27 UTC (permalink / raw)
To: linux-scsi, James Bottomley, Nicholas A. Bellinger, Brian King,
Ian Munsie, Daniel Axtens, Andrew Donnellan
Cc: Michael Neuling, linuxppc-dev, Manoj N. Kumar
When a LUN is removed, the sdev that is associated with the LUN
remains intact until its reference count drops to 0. In order
to prevent an sdev from being removed while a context is still
associated with it, obtain an additional reference per-context
for each LUN attached to the context.
This resolves a potential Oops in the release handler when a
dealing with a LUN that has already been removed.
Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
Suggested-by: Brian King <brking@linux.vnet.ibm.com>
---
drivers/scsi/cxlflash/superpipe.c | 36 ++++++++++++++++++++++++------------
1 file changed, 24 insertions(+), 12 deletions(-)
diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index fa513ba..1fa4af6 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -880,6 +880,9 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
sys_close(lfd);
}
+ /* Release the sdev reference that bound this LUN to the context */
+ scsi_device_put(sdev);
+
out:
if (put_ctx)
put_context(ctxi);
@@ -1287,11 +1290,18 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
}
}
+ rc = scsi_device_get(sdev);
+ if (unlikely(rc)) {
+ dev_err(dev, "%s: Unable to get sdev reference!\n", __func__);
+ goto out;
+ }
+
lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
if (unlikely(!lun_access)) {
dev_err(dev, "%s: Unable to allocate lun_access!\n", __func__);
+ scsi_device_put(sdev);
rc = -ENOMEM;
- goto out;
+ goto err0;
}
lun_access->lli = lli;
@@ -1311,21 +1321,21 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
dev_err(dev, "%s: Could not initialize context %p\n",
__func__, ctx);
rc = -ENODEV;
- goto err0;
+ goto err1;
}
ctxid = cxl_process_element(ctx);
if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
rc = -EPERM;
- goto err1;
+ goto err2;
}
file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
if (unlikely(fd < 0)) {
rc = -ENODEV;
dev_err(dev, "%s: Could not get file descriptor\n", __func__);
- goto err1;
+ goto err2;
}
/* Translate read/write O_* flags from fcntl.h to AFU permission bits */
@@ -1335,7 +1345,7 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
if (unlikely(!ctxi)) {
dev_err(dev, "%s: Failed to create context! (%d)\n",
__func__, ctxid);
- goto err2;
+ goto err3;
}
work = &ctxi->work;
@@ -1346,13 +1356,13 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
if (unlikely(rc)) {
dev_dbg(dev, "%s: Could not start context rc=%d\n",
__func__, rc);
- goto err3;
+ goto err4;
}
rc = afu_attach(cfg, ctxi);
if (unlikely(rc)) {
dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
- goto err4;
+ goto err5;
}
/*
@@ -1388,13 +1398,13 @@ out:
__func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
return rc;
-err4:
+err5:
cxl_stop_context(ctx);
-err3:
+err4:
put_context(ctxi);
destroy_context(cfg, ctxi);
ctxi = NULL;
-err2:
+err3:
/*
* Here, we're overriding the fops with a dummy all-NULL fops because
* fput() calls the release fop, which will cause us to mistakenly
@@ -1406,10 +1416,12 @@ err2:
fput(file);
put_unused_fd(fd);
fd = -1;
-err1:
+err2:
cxl_release_context(ctx);
-err0:
+err1:
kfree(lun_access);
+err0:
+ scsi_device_put(sdev);
goto out;
}
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
2015-09-16 21:27 ` [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal Matthew R. Ochs
@ 2015-09-18 1:26 ` Brian King
2015-09-18 23:18 ` Matthew R. Ochs
2015-09-21 12:11 ` Tomas Henzl
1 sibling, 1 reply; 6+ messages in thread
From: Brian King @ 2015-09-18 1:26 UTC (permalink / raw)
To: Matthew R. Ochs, linux-scsi, James Bottomley,
Nicholas A. Bellinger, Ian Munsie, Daniel Axtens,
Andrew Donnellan
Cc: Michael Neuling, linuxppc-dev, Manoj N. Kumar
On 09/16/2015 04:27 PM, Matthew R. Ochs wrote:
> When a LUN is removed, the sdev that is associated with the LUN
> remains intact until its reference count drops to 0. In order
> to prevent an sdev from being removed while a context is still
> associated with it, obtain an additional reference per-context
> for each LUN attached to the context.
>
> This resolves a potential Oops in the release handler when a
> dealing with a LUN that has already been removed.
>
> Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
> Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
> Suggested-by: Brian King <brking@linux.vnet.ibm.com>
> ---
> drivers/scsi/cxlflash/superpipe.c | 36 ++++++++++++++++++++++++------------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
> index fa513ba..1fa4af6 100644
> --- a/drivers/scsi/cxlflash/superpipe.c
> +++ b/drivers/scsi/cxlflash/superpipe.c
> @@ -880,6 +880,9 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
> sys_close(lfd);
> }
>
> + /* Release the sdev reference that bound this LUN to the context */
> + scsi_device_put(sdev);
> +
> out:
> if (put_ctx)
> put_context(ctxi);
> @@ -1287,11 +1290,18 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> }
> }
>
> + rc = scsi_device_get(sdev);
> + if (unlikely(rc)) {
> + dev_err(dev, "%s: Unable to get sdev reference!\n", __func__);
> + goto out;
> + }
> +
> lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
> if (unlikely(!lun_access)) {
> dev_err(dev, "%s: Unable to allocate lun_access!\n", __func__);
> + scsi_device_put(sdev);
Looks like you've got a double scsi_device_put in this path, since there is another put
in the the err0 path.
> rc = -ENOMEM;
> - goto out;
> + goto err0;
> }
>
> lun_access->lli = lli;
> @@ -1311,21 +1321,21 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> dev_err(dev, "%s: Could not initialize context %p\n",
> __func__, ctx);
> rc = -ENODEV;
> - goto err0;
> + goto err1;
> }
>
> ctxid = cxl_process_element(ctx);
> if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
> dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
> rc = -EPERM;
> - goto err1;
> + goto err2;
> }
>
> file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
> if (unlikely(fd < 0)) {
> rc = -ENODEV;
> dev_err(dev, "%s: Could not get file descriptor\n", __func__);
> - goto err1;
> + goto err2;
> }
>
> /* Translate read/write O_* flags from fcntl.h to AFU permission bits */
> @@ -1335,7 +1345,7 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> if (unlikely(!ctxi)) {
> dev_err(dev, "%s: Failed to create context! (%d)\n",
> __func__, ctxid);
> - goto err2;
> + goto err3;
> }
>
> work = &ctxi->work;
> @@ -1346,13 +1356,13 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> if (unlikely(rc)) {
> dev_dbg(dev, "%s: Could not start context rc=%d\n",
> __func__, rc);
> - goto err3;
> + goto err4;
> }
>
> rc = afu_attach(cfg, ctxi);
> if (unlikely(rc)) {
> dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
> - goto err4;
> + goto err5;
> }
>
> /*
> @@ -1388,13 +1398,13 @@ out:
> __func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
> return rc;
>
> -err4:
> +err5:
> cxl_stop_context(ctx);
> -err3:
> +err4:
> put_context(ctxi);
> destroy_context(cfg, ctxi);
> ctxi = NULL;
> -err2:
> +err3:
> /*
> * Here, we're overriding the fops with a dummy all-NULL fops because
> * fput() calls the release fop, which will cause us to mistakenly
> @@ -1406,10 +1416,12 @@ err2:
> fput(file);
> put_unused_fd(fd);
> fd = -1;
> -err1:
> +err2:
> cxl_release_context(ctx);
> -err0:
> +err1:
> kfree(lun_access);
> +err0:
> + scsi_device_put(sdev);
> goto out;
> }
>
--
Brian King
Power Linux I/O
IBM Linux Technology Center
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
2015-09-18 1:26 ` Brian King
@ 2015-09-18 23:18 ` Matthew R. Ochs
0 siblings, 0 replies; 6+ messages in thread
From: Matthew R. Ochs @ 2015-09-18 23:18 UTC (permalink / raw)
To: Brian King
Cc: linux-scsi, James Bottomley, Nicholas A. Bellinger, Ian Munsie,
Daniel Axtens, Andrew Donnellan, Michael Neuling, linuxppc-dev,
Manoj N. Kumar
> On Sep 17, 2015, at 8:26 PM, Brian King <brking@linux.vnet.ibm.com> =
wrote:
>=20
> On 09/16/2015 04:27 PM, Matthew R. Ochs wrote:
>>=20
>> lun_access =3D kzalloc(sizeof(*lun_access), GFP_KERNEL);
>> if (unlikely(!lun_access)) {
>> dev_err(dev, "%s: Unable to allocate lun_access!\n", =
__func__);
>> + scsi_device_put(sdev);
>=20
> Looks like you've got a double scsi_device_put in this path, since =
there is another put
> in the the err0 path.
Good catch! I'll fix in v3.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
2015-09-16 21:27 ` [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal Matthew R. Ochs
2015-09-18 1:26 ` Brian King
@ 2015-09-21 12:11 ` Tomas Henzl
2015-09-21 22:32 ` Matthew R. Ochs
1 sibling, 1 reply; 6+ messages in thread
From: Tomas Henzl @ 2015-09-21 12:11 UTC (permalink / raw)
To: Matthew R. Ochs, linux-scsi, James Bottomley,
Nicholas A. Bellinger, Brian King, Ian Munsie, Daniel Axtens,
Andrew Donnellan
Cc: Michael Neuling, linuxppc-dev, Manoj N. Kumar
On 16.9.2015 23:27, Matthew R. Ochs wrote:
> When a LUN is removed, the sdev that is associated with the LUN
> remains intact until its reference count drops to 0. In order
> to prevent an sdev from being removed while a context is still
> associated with it, obtain an additional reference per-context
> for each LUN attached to the context.
>
> This resolves a potential Oops in the release handler when a
> dealing with a LUN that has already been removed.
>
> Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
> Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
> Suggested-by: Brian King <brking@linux.vnet.ibm.com>
> ---
> drivers/scsi/cxlflash/superpipe.c | 36 ++++++++++++++++++++++++------------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
> index fa513ba..1fa4af6 100644
> --- a/drivers/scsi/cxlflash/superpipe.c
> +++ b/drivers/scsi/cxlflash/superpipe.c
> @@ -880,6 +880,9 @@ static int _cxlflash_disk_detach(struct scsi_device *sdev,
> sys_close(lfd);
> }
>
> + /* Release the sdev reference that bound this LUN to the context */
> + scsi_device_put(sdev);
> +
I'm not sure here with the use if scsi_device_get+put, also I don't quite well
understand what you are going to fix here and how can it happen.
The scsi_device_get takes an additional module reference, so if used from
a module it shouldn't be held for a long time.
Is it possible for a user to rmmod the czlflash module
after the disk attach function is called?
Cheers,
--tm
> out:
> if (put_ctx)
> put_context(ctxi);
> @@ -1287,11 +1290,18 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> }
> }
>
> + rc = scsi_device_get(sdev);
> + if (unlikely(rc)) {
> + dev_err(dev, "%s: Unable to get sdev reference!\n", __func__);
> + goto out;
> + }
> +
> lun_access = kzalloc(sizeof(*lun_access), GFP_KERNEL);
> if (unlikely(!lun_access)) {
> dev_err(dev, "%s: Unable to allocate lun_access!\n", __func__);
> + scsi_device_put(sdev);
> rc = -ENOMEM;
> - goto out;
> + goto err0;
> }
>
> lun_access->lli = lli;
> @@ -1311,21 +1321,21 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> dev_err(dev, "%s: Could not initialize context %p\n",
> __func__, ctx);
> rc = -ENODEV;
> - goto err0;
> + goto err1;
> }
>
> ctxid = cxl_process_element(ctx);
> if (unlikely((ctxid > MAX_CONTEXT) || (ctxid < 0))) {
> dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
> rc = -EPERM;
> - goto err1;
> + goto err2;
> }
>
> file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
> if (unlikely(fd < 0)) {
> rc = -ENODEV;
> dev_err(dev, "%s: Could not get file descriptor\n", __func__);
> - goto err1;
> + goto err2;
> }
>
> /* Translate read/write O_* flags from fcntl.h to AFU permission bits */
> @@ -1335,7 +1345,7 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> if (unlikely(!ctxi)) {
> dev_err(dev, "%s: Failed to create context! (%d)\n",
> __func__, ctxid);
> - goto err2;
> + goto err3;
> }
>
> work = &ctxi->work;
> @@ -1346,13 +1356,13 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
> if (unlikely(rc)) {
> dev_dbg(dev, "%s: Could not start context rc=%d\n",
> __func__, rc);
> - goto err3;
> + goto err4;
> }
>
> rc = afu_attach(cfg, ctxi);
> if (unlikely(rc)) {
> dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
> - goto err4;
> + goto err5;
> }
>
> /*
> @@ -1388,13 +1398,13 @@ out:
> __func__, ctxid, fd, attach->block_size, rc, attach->last_lba);
> return rc;
>
> -err4:
> +err5:
> cxl_stop_context(ctx);
> -err3:
> +err4:
> put_context(ctxi);
> destroy_context(cfg, ctxi);
> ctxi = NULL;
> -err2:
> +err3:
> /*
> * Here, we're overriding the fops with a dummy all-NULL fops because
> * fput() calls the release fop, which will cause us to mistakenly
> @@ -1406,10 +1416,12 @@ err2:
> fput(file);
> put_unused_fd(fd);
> fd = -1;
> -err1:
> +err2:
> cxl_release_context(ctx);
> -err0:
> +err1:
> kfree(lun_access);
> +err0:
> + scsi_device_put(sdev);
> goto out;
> }
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal
2015-09-21 12:11 ` Tomas Henzl
@ 2015-09-21 22:32 ` Matthew R. Ochs
0 siblings, 0 replies; 6+ messages in thread
From: Matthew R. Ochs @ 2015-09-21 22:32 UTC (permalink / raw)
To: Tomas Henzl
Cc: linux-scsi, James Bottomley, Nicholas A. Bellinger, Brian King,
Ian Munsie, Daniel Axtens, Andrew Donnellan, Michael Neuling,
linuxppc-dev, Manoj N. Kumar
> On Sep 21, 2015, at 7:11 AM, Tomas Henzl <thenzl@redhat.com> wrote:
> On 16.9.2015 23:27, Matthew R. Ochs wrote:
>> When a LUN is removed, the sdev that is associated with the LUN
>> remains intact until its reference count drops to 0. In order
>> to prevent an sdev from being removed while a context is still
>> associated with it, obtain an additional reference per-context
>> for each LUN attached to the context.
>>=20
>> This resolves a potential Oops in the release handler when a
>> dealing with a LUN that has already been removed.
>>=20
>> Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
>> Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
>> Suggested-by: Brian King <brking@linux.vnet.ibm.com>
>> ---
>> drivers/scsi/cxlflash/superpipe.c | 36 =
++++++++++++++++++++++++------------
>> 1 file changed, 24 insertions(+), 12 deletions(-)
>>=20
>> diff --git a/drivers/scsi/cxlflash/superpipe.c =
b/drivers/scsi/cxlflash/superpipe.c
>> index fa513ba..1fa4af6 100644
>> --- a/drivers/scsi/cxlflash/superpipe.c
>> +++ b/drivers/scsi/cxlflash/superpipe.c
>> @@ -880,6 +880,9 @@ static int _cxlflash_disk_detach(struct =
scsi_device *sdev,
>> sys_close(lfd);
>> }
>>=20
>> + /* Release the sdev reference that bound this LUN to the context =
*/
>> + scsi_device_put(sdev);
>> +
>=20
> I'm not sure here with the use if scsi_device_get+put, also I don't =
quite well
> understand what you are going to fix here and how can it happen.
> The scsi_device_get takes an additional module reference, so if used =
from
> a module it shouldn't be held for a long time.
The issue here is that the user context needs to be bound to the device =
so that
in the event that device goes away, it doesn't completely go away until =
the user
context is done using it. Without it, it is possible to crash when the =
context is
being freed.
Essentially this is the same as incrementing the count when an open is =
performed
on the device. The device can be removed (and is hidden upon doing so) =
but is
not actually freed until the reference is resolved (close()).
> Is it possible for a user to rmmod the czlflash module
> after the disk attach function is called?
Not while a user is present.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2015-09-21 22:32 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-09-16 16:52 [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal Matthew R. Ochs
-- strict thread matches above, loose matches on Subject: below --
2015-09-16 21:23 [PATCH v2 00/30] cxlflash: Miscellaneous bug fixes and corrections Matthew R. Ochs
2015-09-16 21:27 ` [PATCH v2 04/30] cxlflash: Fix potential oops following LUN removal Matthew R. Ochs
2015-09-18 1:26 ` Brian King
2015-09-18 23:18 ` Matthew R. Ochs
2015-09-21 12:11 ` Tomas Henzl
2015-09-21 22:32 ` Matthew R. Ochs
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).