Op 27-01-15 om 09:25 schreef Sumit Semwal: > Add some helpers to share the constraints of devices while attaching > to the dmabuf buffer. > > At each attach, the constraints are calculated based on the following: > - max_segment_size, max_segment_count, segment_boundary_mask from > device_dma_parameters. > > In case the attaching device's constraints don't match up, attach() fails. > > At detach, the constraints are recalculated based on the remaining > attached devices. > > Two helpers are added: > - dma_buf_get_constraints - which gives the current constraints as calculated > during each attach on the buffer till the time, > - dma_buf_recalc_constraints - which recalculates the constraints for all > currently attached devices for the 'paranoid' ones amongst us. > > The idea of this patch is largely taken from Rob Clark's RFC at > https://lkml.org/lkml/2012/7/19/285, and the comments received on it. > > Cc: Rob Clark <robdclark@xxxxxxxxx> > Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx> > --- > v3: > - Thanks to Russell's comment, remove dma_mask and coherent_dma_mask from > constraints' calculation; has a nice side effect of letting us use > device_dma_parameters directly to list constraints. > - update the debugfs output to show constraint info as well. > > v2: split constraints-sharing and allocation helpers > > drivers/dma-buf/dma-buf.c | 126 +++++++++++++++++++++++++++++++++++++++++++++- > include/linux/dma-buf.h | 7 +++ > 2 files changed, 132 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 5be225c2ba98..f363f1440803 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -264,6 +264,66 @@ static inline int is_dma_buf_file(struct file *file) > return file->f_op == &dma_buf_fops; > } > > +static inline void init_constraints(struct device_dma_parameters *cons) > +{ > + cons->max_segment_count = (unsigned int)-1; > + cons->max_segment_size = (unsigned int)-1; > + cons->segment_boundary_mask = (unsigned long)-1; > +} Use DMA_SEGMENTS_MAX_SEG_COUNT or UINT/ULONG_MAX here instead? Patches look sane, Reviewed-By: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxx> > +/* > + * calc_constraints - calculates if the new attaching device's constraints > + * match, with the constraints of already attached devices; if yes, returns > + * the constraints; else return ERR_PTR(-EINVAL) > + */ > +static int calc_constraints(struct device *dev, > + struct device_dma_parameters *calc_cons) > +{ > + struct device_dma_parameters cons = *calc_cons; > + > + cons.max_segment_count = min(cons.max_segment_count, > + dma_get_max_seg_count(dev)); > + cons.max_segment_size = min(cons.max_segment_size, > + dma_get_max_seg_size(dev)); > + cons.segment_boundary_mask &= dma_get_seg_boundary(dev); > + > + if (!cons.max_segment_count || > + !cons.max_segment_size || > + !cons.segment_boundary_mask) { > + pr_err("Dev: %s's constraints don't match\n", dev_name(dev)); > + return -EINVAL; > + } > + > + *calc_cons = cons; > + > + return 0; > +} > + > +/* > + * recalc_constraints - recalculates constraints for all attached devices; > + * useful for detach() recalculation, and for dma_buf_recalc_constraints() > + * helper. > + * Returns recalculated constraints in recalc_cons, or error in the unlikely > + * case when constraints of attached devices might have changed. > + */ > +static int recalc_constraints(struct dma_buf *dmabuf, > + struct device_dma_parameters *recalc_cons) > +{ > + struct device_dma_parameters calc_cons; > + struct dma_buf_attachment *attach; > + int ret = 0; > + > + init_constraints(&calc_cons); > + > + list_for_each_entry(attach, &dmabuf->attachments, node) { > + ret = calc_constraints(attach->dev, &calc_cons); > + if (ret) > + return ret; > + } > + *recalc_cons = calc_cons; > + return 0; > +} > + > /** > * dma_buf_export_named - Creates a new dma_buf, and associates an anon file > * with this buffer, so it can be exported. > @@ -313,6 +373,9 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops, > dmabuf->ops = ops; > dmabuf->size = size; > dmabuf->exp_name = exp_name; > + > + init_constraints(&dmabuf->constraints); > + > init_waitqueue_head(&dmabuf->poll); > dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll; > dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0; > @@ -422,7 +485,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > struct device *dev) > { > struct dma_buf_attachment *attach; > - int ret; > + int ret = 0; > > if (WARN_ON(!dmabuf || !dev)) > return ERR_PTR(-EINVAL); > @@ -436,6 +499,9 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > > mutex_lock(&dmabuf->lock); > > + if (calc_constraints(dev, &dmabuf->constraints)) > + goto err_constraints; > + > if (dmabuf->ops->attach) { > ret = dmabuf->ops->attach(dmabuf, dev, attach); > if (ret) > @@ -448,6 +514,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, > > err_attach: > kfree(attach); > +err_constraints: > mutex_unlock(&dmabuf->lock); > return ERR_PTR(ret); > } > @@ -470,6 +537,8 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) > if (dmabuf->ops->detach) > dmabuf->ops->detach(dmabuf, attach); > > + recalc_constraints(dmabuf, &dmabuf->constraints); > + > mutex_unlock(&dmabuf->lock); > kfree(attach); > } > @@ -770,6 +839,56 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) > } > EXPORT_SYMBOL_GPL(dma_buf_vunmap); > > +/** > + * dma_buf_get_constraints - get the *current* constraints of the dmabuf, > + * as calculated during each attach(); returns error on invalid inputs > + * > + * @dmabuf: [in] buffer to get constraints of > + * @constraints: [out] current constraints are returned in this > + */ > +int dma_buf_get_constraints(struct dma_buf *dmabuf, > + struct device_dma_parameters *constraints) > +{ > + if (WARN_ON(!dmabuf || !constraints)) > + return -EINVAL; > + > + mutex_lock(&dmabuf->lock); > + *constraints = dmabuf->constraints; > + mutex_unlock(&dmabuf->lock); > + return 0; > +} > +EXPORT_SYMBOL_GPL(dma_buf_get_constraints); > + > +/** > + * dma_buf_recalc_constraints - *recalculate* the constraints for the buffer > + * afresh, from the list of currently attached devices; this could be useful > + * cross-check the current constraints, for exporters that might want to be > + * 'paranoid' about the device constraints. > + * > + * returns error on invalid inputs > + * > + * @dmabuf: [in] buffer to get constraints of > + * @constraints: [out] recalculated constraints are returned in this > + */ > +int dma_buf_recalc_constraints(struct dma_buf *dmabuf, > + struct device_dma_parameters *constraints) > +{ > + struct device_dma_parameters calc_cons; > + int ret = 0; > + > + if (WARN_ON(!dmabuf || !constraints)) > + return -EINVAL; > + > + mutex_lock(&dmabuf->lock); > + ret = recalc_constraints(dmabuf, &calc_cons); > + if (!ret) > + *constraints = calc_cons; > + > + mutex_unlock(&dmabuf->lock); > + return ret; > +} > +EXPORT_SYMBOL_GPL(dma_buf_recalc_constraints); > + > #ifdef CONFIG_DEBUG_FS > static int dma_buf_describe(struct seq_file *s) > { > @@ -801,6 +920,11 @@ static int dma_buf_describe(struct seq_file *s) > buf_obj->file->f_flags, buf_obj->file->f_mode, > file_count(buf_obj->file), > buf_obj->exp_name); > + seq_printf(s, "\tConstraints: Seg Count: %08u, Seg Size: %08u", > + buf_obj->constraints.max_segment_count, > + buf_obj->constraints.max_segment_size); > + seq_printf(s, " seg boundary mask: %08lx\n", > + buf_obj->constraints.segment_boundary_mask); > > seq_puts(s, "\tAttached Devices:\n"); > attach_count = 0; > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index 694e1fe1c4b4..489ad9b2e5ae 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -34,6 +34,7 @@ > #include <linux/wait.h> > > struct device; > +struct device_dma_parameters; > struct dma_buf; > struct dma_buf_attachment; > > @@ -116,6 +117,7 @@ struct dma_buf_ops { > * @ops: dma_buf_ops associated with this buffer object. > * @exp_name: name of the exporter; useful for debugging. > * @list_node: node for dma_buf accounting and debugging. > + * @constraints: calculated constraints of attached devices. > * @priv: exporter specific private data for this buffer object. > * @resv: reservation object linked to this dma-buf > */ > @@ -130,6 +132,7 @@ struct dma_buf { > void *vmap_ptr; > const char *exp_name; > struct list_head list_node; > + struct device_dma_parameters constraints; > void *priv; > struct reservation_object *resv; > > @@ -211,4 +214,8 @@ void *dma_buf_vmap(struct dma_buf *); > void dma_buf_vunmap(struct dma_buf *, void *vaddr); > int dma_buf_debugfs_create_file(const char *name, > int (*write)(struct seq_file *)); > + > +int dma_buf_get_constraints(struct dma_buf *, struct device_dma_parameters *); > +int dma_buf_recalc_constraints(struct dma_buf *, > + struct device_dma_parameters *); > #endif /* __DMA_BUF_H__ */ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
