Messages in this thread Patch in this message | | | Date | Fri, 11 Apr 2008 11:07:39 +0200 | From | Uwe Kleine-König <> | Subject | [PATCH 1/4 v2] UIO: hold a reference to the device's owner while the device is open |
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Otherwise the device might just disappear while /dev/uioX is being used which results in an Oops.
Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com> ---
Hans J. Koch wrote: > > > The label err_module_get should probably be omitted because it's used only > > > once and has just one line of code. You could simply write "return ret" > > > instead of "goto err_module_get". > > This makes code shuffling easier. For example if someone decides that > > try_module_get should be done after allocating listener then you only > > have to exchange the two corresponding code blocks and the two groups > > (label + cleanup) in the error handling block. > > If the error handling is spread over the whole functions you can easily > > miss something---as happend above. :-) > > Well, it depends. It's all about readability. Any function should be > written in a way that makes it as clear as possible what it does. Your > code is certainly not critical regarding that aspect, but I think it can > still be improved. And a label that is used only once and contains only > one line of code is definetly unnecessary. I don't follow the > maybe-one-day-in-the-future-it-might-be-useful philosophy. I like code > that is as clean and readable as possible _now_. That thing about code reordering is minor compared to having all error handling in one place, but ...
> And as this patch is > not just a driver but affects the UIO core, this is even more important. > > Could you please send an updated patch? ... , it's your code, so you can find a new version below.
Best regards Uwe
drivers/uio/uio.c | 36 +++++++++++++++++++++--------------- 1 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 1175908..55cc7b8 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -301,23 +301,33 @@ static int uio_open(struct inode *inode, struct file *filep) if (!idev) return -ENODEV; + if (!try_module_get(idev->owner)) + return -ENODEV; + listener = kmalloc(sizeof(*listener), GFP_KERNEL); - if (!listener) - return -ENOMEM; + if (!listener) { + ret = -ENOMEM; + goto err_alloc_listener; + } listener->dev = idev; listener->event_count = atomic_read(&idev->event); filep->private_data = listener; if (idev->info->open) { - if (!try_module_get(idev->owner)) - return -ENODEV; ret = idev->info->open(idev->info, inode); - module_put(idev->owner); + if (ret) + goto err_infoopen; } - if (ret) - kfree(listener); + return 0; + +err_infoopen: + + kfree(listener); +err_alloc_listener: + + module_put(idev->owner); return ret; } @@ -336,12 +346,11 @@ static int uio_release(struct inode *inode, struct file *filep) struct uio_listener *listener = filep->private_data; struct uio_device *idev = listener->dev; - if (idev->info->release) { - if (!try_module_get(idev->owner)) - return -ENODEV; + if (idev->info->release) ret = idev->info->release(idev->info, inode); - module_put(idev->owner); - } + + module_put(idev->owner); + if (filep->f_flags & FASYNC) ret = uio_fasync(-1, filep, 0); kfree(listener); @@ -510,10 +519,7 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma) return -EINVAL; if (idev->info->mmap) { - if (!try_module_get(idev->owner)) - return -ENODEV; ret = idev->info->mmap(idev->info, vma); - module_put(idev->owner); return ret; } -- 1.5.4.5
-- Uwe Kleine-König, Software Engineer Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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