| Message ID | 20200715092528.8136-2-brgl@bgdev.pl (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | devres: provide and use devm_krealloc() | expand |
On Wed, Jul 15, 2020 at 11:25:26AM +0200, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > Implement the managed variant of krealloc(). This function works with > all memory allocated by devm_kmalloc() (or devres functions using it > implicitly like devm_kmemdup(), devm_kstrdup() etc.). > > Managed realloc'ed chunks can be manually released with devm_kfree(). FWIW, Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > --- > .../driver-api/driver-model/devres.rst | 1 + > drivers/base/devres.c | 68 +++++++++++++++++++ > include/linux/device.h | 2 + > 3 files changed, 71 insertions(+) > > diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst > index eaaaafc21134f..f318a5c0033c1 100644 > --- a/Documentation/driver-api/driver-model/devres.rst > +++ b/Documentation/driver-api/driver-model/devres.rst > @@ -354,6 +354,7 @@ MEM > devm_kmalloc() > devm_kmalloc_array() > devm_kmemdup() > + devm_krealloc() > devm_kstrdup() > devm_kvasprintf() > devm_kzalloc() > diff --git a/drivers/base/devres.c b/drivers/base/devres.c > index ed615d3b9cf15..24e27959af270 100644 > --- a/drivers/base/devres.c > +++ b/drivers/base/devres.c > @@ -837,6 +837,74 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) > } > EXPORT_SYMBOL_GPL(devm_kmalloc); > > +/** > + * devm_krealloc - Resource-managed krealloc() > + * @dev: Device to re-allocate memory for > + * @ptr: Pointer to the memory chunk to re-allocate > + * @new_size: New allocation size > + * @gfp: Allocation gfp flags > + * > + * Managed krealloc(). Resizes the memory chunk allocated with devm_kmalloc(). > + * Behaves similarly to regular krealloc(): if @ptr is NULL or ZERO_SIZE_PTR, > + * it's the equivalent of devm_kmalloc(). If new_size is zero, it frees the > + * previously allocated memory and returns ZERO_SIZE_PTR. This function doesn't > + * change the order in which the release callback for the re-alloc'ed devres > + * will be called (except when falling back to devm_kmalloc() or when freeing > + * resources when new_size is zero). The contents of the memory are preserved > + * up to the lesser of new and old sizes. > + */ > +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp) > +{ > + struct devres *old_dr, *new_dr; > + struct list_head old_head; > + unsigned long flags; > + size_t total_size; > + void *ret = NULL; > + > + if (unlikely(!new_size)) { > + devm_kfree(dev, ptr); > + return ZERO_SIZE_PTR; > + } > + > + if (unlikely(ZERO_OR_NULL_PTR(ptr))) > + return devm_kmalloc(dev, new_size, gfp); > + > + if (WARN_ON(is_kernel_rodata((unsigned long)ptr))) > + /* > + * We cannot reliably realloc a const string returned by > + * devm_kstrdup_const(). > + */ > + return NULL; > + > + if (!check_dr_size(new_size, &total_size)) > + return NULL; > + > + spin_lock_irqsave(&dev->devres_lock, flags); > + > + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr); > + if (!old_dr) { > + spin_unlock_irqrestore(&dev->devres_lock, flags); > + WARN(1, "Memory chunk not managed or managed by a different device."); > + return NULL; > + } > + > + old_head = old_dr->node.entry; > + > + new_dr = krealloc(old_dr, total_size, gfp); > + if (!new_dr) { > + spin_unlock_irqrestore(&dev->devres_lock, flags); > + return NULL; > + } > + > + if (new_dr != old_dr) > + list_replace(&old_head, &new_dr->node.entry); > + > + ret = new_dr->data; > + spin_unlock_irqrestore(&dev->devres_lock, flags); > + return ret; > +} > +EXPORT_SYMBOL_GPL(devm_krealloc); > + > /** > * devm_kstrdup - Allocate resource managed space and > * copy an existing string into that. > diff --git a/include/linux/device.h b/include/linux/device.h > index 7322c51e9c0c7..f64f408431593 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -206,6 +206,8 @@ int devres_release_group(struct device *dev, void *id); > > /* managed devm_k.alloc/kfree for device drivers */ > void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc; > +void *devm_krealloc(struct device *dev, void *ptr, size_t size, > + gfp_t gfp) __must_check; > __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp, > const char *fmt, va_list ap) __malloc; > __printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp, > -- > 2.26.1 >
On Wed, Jul 15, 2020 at 11:25 AM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > Implement the managed variant of krealloc(). This function works with > all memory allocated by devm_kmalloc() (or devres functions using it > implicitly like devm_kmemdup(), devm_kstrdup() etc.). > > Managed realloc'ed chunks can be manually released with devm_kfree(). > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > --- [snip!] > +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp) > +{ > + struct devres *old_dr, *new_dr; > + struct list_head old_head; > + unsigned long flags; > + size_t total_size; > + void *ret = NULL; > + > + if (unlikely(!new_size)) { > + devm_kfree(dev, ptr); > + return ZERO_SIZE_PTR; > + } > + > + if (unlikely(ZERO_OR_NULL_PTR(ptr))) > + return devm_kmalloc(dev, new_size, gfp); > + > + if (WARN_ON(is_kernel_rodata((unsigned long)ptr))) > + /* > + * We cannot reliably realloc a const string returned by > + * devm_kstrdup_const(). > + */ > + return NULL; > + > + if (!check_dr_size(new_size, &total_size)) > + return NULL; > + > + spin_lock_irqsave(&dev->devres_lock, flags); > + > + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr); > + if (!old_dr) { > + spin_unlock_irqrestore(&dev->devres_lock, flags); > + WARN(1, "Memory chunk not managed or managed by a different device."); > + return NULL; > + } > + > + old_head = old_dr->node.entry; > + > + new_dr = krealloc(old_dr, total_size, gfp); Ugh, I wanted to check up on this patch and, after looking at it now, realized it's wrong. If the user calls devm_krealloc() with GFP_KERNEL we may end up sleeping with spinlock taken. Let me prepare another version. Bartosz
diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index eaaaafc21134f..f318a5c0033c1 100644 --- a/Documentation/driver-api/driver-model/devres.rst +++ b/Documentation/driver-api/driver-model/devres.rst @@ -354,6 +354,7 @@ MEM devm_kmalloc() devm_kmalloc_array() devm_kmemdup() + devm_krealloc() devm_kstrdup() devm_kvasprintf() devm_kzalloc() diff --git a/drivers/base/devres.c b/drivers/base/devres.c index ed615d3b9cf15..24e27959af270 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -837,6 +837,74 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) } EXPORT_SYMBOL_GPL(devm_kmalloc); +/** + * devm_krealloc - Resource-managed krealloc() + * @dev: Device to re-allocate memory for + * @ptr: Pointer to the memory chunk to re-allocate + * @new_size: New allocation size + * @gfp: Allocation gfp flags + * + * Managed krealloc(). Resizes the memory chunk allocated with devm_kmalloc(). + * Behaves similarly to regular krealloc(): if @ptr is NULL or ZERO_SIZE_PTR, + * it's the equivalent of devm_kmalloc(). If new_size is zero, it frees the + * previously allocated memory and returns ZERO_SIZE_PTR. This function doesn't + * change the order in which the release callback for the re-alloc'ed devres + * will be called (except when falling back to devm_kmalloc() or when freeing + * resources when new_size is zero). The contents of the memory are preserved + * up to the lesser of new and old sizes. + */ +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp) +{ + struct devres *old_dr, *new_dr; + struct list_head old_head; + unsigned long flags; + size_t total_size; + void *ret = NULL; + + if (unlikely(!new_size)) { + devm_kfree(dev, ptr); + return ZERO_SIZE_PTR; + } + + if (unlikely(ZERO_OR_NULL_PTR(ptr))) + return devm_kmalloc(dev, new_size, gfp); + + if (WARN_ON(is_kernel_rodata((unsigned long)ptr))) + /* + * We cannot reliably realloc a const string returned by + * devm_kstrdup_const(). + */ + return NULL; + + if (!check_dr_size(new_size, &total_size)) + return NULL; + + spin_lock_irqsave(&dev->devres_lock, flags); + + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr); + if (!old_dr) { + spin_unlock_irqrestore(&dev->devres_lock, flags); + WARN(1, "Memory chunk not managed or managed by a different device."); + return NULL; + } + + old_head = old_dr->node.entry; + + new_dr = krealloc(old_dr, total_size, gfp); + if (!new_dr) { + spin_unlock_irqrestore(&dev->devres_lock, flags); + return NULL; + } + + if (new_dr != old_dr) + list_replace(&old_head, &new_dr->node.entry); + + ret = new_dr->data; + spin_unlock_irqrestore(&dev->devres_lock, flags); + return ret; +} +EXPORT_SYMBOL_GPL(devm_krealloc); + /** * devm_kstrdup - Allocate resource managed space and * copy an existing string into that. diff --git a/include/linux/device.h b/include/linux/device.h index 7322c51e9c0c7..f64f408431593 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -206,6 +206,8 @@ int devres_release_group(struct device *dev, void *id); /* managed devm_k.alloc/kfree for device drivers */ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc; +void *devm_krealloc(struct device *dev, void *ptr, size_t size, + gfp_t gfp) __must_check; __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt, va_list ap) __malloc; __printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp,