Hi Vinod, > -----Original Message----- > From: Vinod Koul [mailto:vkoul@xxxxxxxxxx] > Sent: Monday, May 4, 2020 10:46 AM > To: Rafał Hibner <rafal.hibner@xxxxxxxxxxxx> > Cc: Appana Durga Kedareswara Rao <appanad@xxxxxxxxxx>; Radhey Shyam > Pandey <radheys@xxxxxxxxxx>; Harini Katakam <harinik@xxxxxxxxxx>; Dan > Williams <dan.j.williams@xxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>; open > list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM > <dmaengine@xxxxxxxxxxxxxxx>; moderated list:ARM/ZYNQ ARCHITECTURE > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list <linux- > kernel@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH] dma: zynqmp_dma: Initialize descriptor list after freeing > during reset > > On 02-05-20, 15:00, Rafał Hibner wrote: > > Hello Vinod, > > > > On 02.05.2020 14:32, Vinod Koul wrote: > > > Would it not be better to use list_del_init() where we delete it > > > rather than do the init here? > > > > > > > It is not a problem of list element itself not being initialized. > > The problem is that during fault conditions (zynqmp_dma_reset) all > > elements are moved to free list. List head however is not reinitialized. > > > > In normal flow elements are removed by list_del and resubmitted to > > free list with zynqmp_dma_free_descriptor. > > > > static void zynqmp_dma_chan_desc_cleanup(struct zynqmp_dma_chan *chan) > > { > > ... > > list_for_each_entry_safe(desc, next, &chan->done_list, node) { > > ... > > list_del(&desc->node); > > ... > > zynqmp_dma_free_descriptor(chan, desc); > > } > > } > > > > The zynqmp_dma_free_descriptor does not delete elements from the list > > by itself. > > I am not he author of this driver so I fixed it by doing non intrusive > > changes. > > > > Anyways, I do not see how using list_del_init would fix the bug. > > Looking at this, i think it would make sense to do list_splice_init() before we > send the list to be freed. > > Radhey/Appana are cced, they should test this. I tested this patch (I took over from Appana Kedar). Once this discussion concludes and Rafal sends a v2, I'll test again and add my tag. Regards, Harini
