On 20.03.2017 21:44, Mikko Perttunen wrote:
> This is largely a rewrite of the Host1x channel allocation
> code in channel.c, bringing several changes:
>
> - The previous code could deadlock due to an interaction
> between the 'reflock' mutex and CDMA timeout handling.
> This gets rid of the mutex.
> - In the future, per-user channel allocation will be
> useful to have. This paves the way for that by allowing
> host1x_channel_request to wait for a free channel, and
> freeing channels when their refcount drops to zero.
> - Support for more than 32 channels, required for Tegra186
> - General refactoring, including better encapsulation
> of channel ownership handling into channel.c
>
> Signed-off-by: Mikko Perttunen <[email protected]>
> ---
> Ran though test suite at github.com/cyndis/host1x_test.
> Fixes the timeout test there.
>
> drivers/gpu/drm/tegra/gr2d.c | 6 +-
> drivers/gpu/drm/tegra/gr3d.c | 6 +-
> drivers/gpu/drm/tegra/vic.c | 6 +-
> drivers/gpu/host1x/cdma.c | 2 +-
> drivers/gpu/host1x/channel.c | 154
> +++++++++++++++++++++++--------------
> drivers/gpu/host1x/channel.h | 28 ++++---
> drivers/gpu/host1x/debug.c | 49 +++++-------
> drivers/gpu/host1x/dev.c | 6 +-
> drivers/gpu/host1x/dev.h | 8 +-
> drivers/gpu/host1x/hw/channel_hw.c | 12 +--
> include/linux/host1x.h | 1 -
> 11 files changed, 155 insertions(+), 123 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
> index 02cd3e37a6ec..936ce1a55987 100644
> --- a/drivers/gpu/drm/tegra/gr2d.c
> +++ b/drivers/gpu/drm/tegra/gr2d.c
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 2012-2013, NVIDIA Corporation.
> + * Copyright (c) 2012-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> @@ -38,7 +38,7 @@ static int gr2d_init(struct host1x_client *client)
>
> client->syncpts[0] = host1x_syncpt_request(client->dev, flags);
> if (!client->syncpts[0]) {
> - host1x_channel_free(gr2d->channel);
> + host1x_channel_put(gr2d->channel);
> return -ENOMEM;
> }
>
> @@ -57,7 +57,7 @@ static int gr2d_exit(struct host1x_client *client)
> return err;
>
> host1x_syncpt_free(client->syncpts[0]);
> - host1x_channel_free(gr2d->channel);
> + host1x_channel_put(gr2d->channel);
>
> return 0;
> }
> diff --git a/drivers/gpu/drm/tegra/gr3d.c b/drivers/gpu/drm/tegra/gr3d.c
> index 13f0d1b7cd98..da02230c58ef 100644
> --- a/drivers/gpu/drm/tegra/gr3d.c
> +++ b/drivers/gpu/drm/tegra/gr3d.c
> @@ -1,6 +1,6 @@
> /*
> * Copyright (C) 2013 Avionic Design GmbH
> - * Copyright (C) 2013 NVIDIA Corporation
> + * Copyright (C) 2013-2017 NVIDIA Corporation
> *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> @@ -48,7 +48,7 @@ static int gr3d_init(struct host1x_client *client)
>
> client->syncpts[0] = host1x_syncpt_request(client->dev, flags);
> if (!client->syncpts[0]) {
> - host1x_channel_free(gr3d->channel);
> + host1x_channel_put(gr3d->channel);
> return -ENOMEM;
> }
>
> @@ -67,7 +67,7 @@ static int gr3d_exit(struct host1x_client *client)
> return err;
>
> host1x_syncpt_free(client->syncpts[0]);
> - host1x_channel_free(gr3d->channel);
> + host1x_channel_put(gr3d->channel);
>
> return 0;
> }
> diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
> index cd804e404a11..5a36adfc01f6 100644
> --- a/drivers/gpu/drm/tegra/vic.c
> +++ b/drivers/gpu/drm/tegra/vic.c
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (c) 2015, NVIDIA Corporation.
> + * Copyright (c) 2015-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> @@ -182,7 +182,7 @@ static int vic_init(struct host1x_client *client)
> free_syncpt:
> host1x_syncpt_free(client->syncpts[0]);
> free_channel:
> - host1x_channel_free(vic->channel);
> + host1x_channel_put(vic->channel);
> detach_device:
> if (tegra->domain)
> iommu_detach_device(tegra->domain, vic->dev);
> @@ -203,7 +203,7 @@ static int vic_exit(struct host1x_client *client)
> return err;
>
> host1x_syncpt_free(client->syncpts[0]);
> - host1x_channel_free(vic->channel);
> + host1x_channel_put(vic->channel);
>
> if (vic->domain) {
> iommu_detach_device(vic->domain, vic->dev);
> diff --git a/drivers/gpu/host1x/cdma.c b/drivers/gpu/host1x/cdma.c
> index 28541b280739..d7c1e269ed67 100644
> --- a/drivers/gpu/host1x/cdma.c
> +++ b/drivers/gpu/host1x/cdma.c
> @@ -1,7 +1,7 @@
> /*
> * Tegra host1x Command DMA
> *
> - * Copyright (c) 2010-2013, NVIDIA Corporation.
> + * Copyright (c) 2010-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms and conditions of the GNU General Public License,
> diff --git a/drivers/gpu/host1x/channel.c b/drivers/gpu/host1x/channel.c
> index 8f437d924c10..819e97ccb00d 100644
> --- a/drivers/gpu/host1x/channel.c
> +++ b/drivers/gpu/host1x/channel.c
> @@ -1,7 +1,7 @@
> /*
> * Tegra host1x Channel
> *
> - * Copyright (c) 2010-2013, NVIDIA Corporation.
> + * Copyright (c) 2010-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms and conditions of the GNU General Public License,
> @@ -24,19 +24,36 @@
> #include "job.h"
>
> /* Constructor for the host1x device list */
> -int host1x_channel_list_init(struct host1x *host)
> +int host1x_channel_list_init(struct host1x_channel_list *chlist,
> + unsigned int num_channels)
> {
> - INIT_LIST_HEAD(&host->chlist.list);
> - mutex_init(&host->chlist_mutex);
> -
> - if (host->info->nb_channels > BITS_PER_LONG) {
> - WARN(1, "host1x hardware has more channels than supported by
> the driver\n");
> - return -ENOSYS;
> + chlist->channels = kcalloc(num_channels, sizeof(struct host1x_channel),
> + GFP_KERNEL);
> + if (!chlist->channels)
> + return -ENOMEM;
> +
> + chlist->allocated_channels =
> + kcalloc(BITS_TO_LONGS(num_channels), sizeof(unsigned long),
> + GFP_KERNEL);
> + if (!chlist->allocated_channels) {
> + kfree(chlist->channels);
> + return -ENOMEM;
> }
>
> + bitmap_zero(chlist->allocated_channels, num_channels);
> +
> + mutex_init(&chlist->alloc_lock);
> + sema_init(&chlist->alloc_sema, num_channels);
> +
> return 0;
> }
>
> +void host1x_channel_list_free(struct host1x_channel_list *chlist)
> +{
> + kfree(chlist->allocated_channels);
> + kfree(chlist->channels);
> +}
> +
> int host1x_job_submit(struct host1x_job *job)
> {
> struct host1x *host = dev_get_drvdata(job->channel->dev->parent);
> @@ -47,86 +64,107 @@ EXPORT_SYMBOL(host1x_job_submit);
>
> struct host1x_channel *host1x_channel_get(struct host1x_channel *channel)
> {
> - int err = 0;
> -
> - mutex_lock(&channel->reflock);
> -
> - if (channel->refcount == 0)
> - err = host1x_cdma_init(&channel->cdma);
> + kref_get(&channel->refcount);
>
> - if (!err)
> - channel->refcount++;
> + return channel;
> +}
> +EXPORT_SYMBOL(host1x_channel_get);
>
> - mutex_unlock(&channel->reflock);
> +/**
> + * host1x_channel_get_index() - Attempt to get channel reference by index
> + * @host: Host1x device object
> + * @index: Index of channel
> + *
> + * If channel number @index is currently allocated, increase its refcount
> + * and return a pointer to it. Otherwise, return NULL.
> + */
> +struct host1x_channel *host1x_channel_get_index(struct host1x *host,
> + unsigned int index)
> +{
> + struct host1x_channel *ch = &host->channel_list.channels[index];
>
> - return err ? NULL : channel;
> + if (kref_get_unless_zero(&ch->refcount))
> + return ch;
> + else
> + return NULL;
> }
> -EXPORT_SYMBOL(host1x_channel_get);
>
> -void host1x_channel_put(struct host1x_channel *channel)
> +static void release_channel(struct kref *kref)
> {
> - mutex_lock(&channel->reflock);
> + struct host1x_channel *channel =
> + container_of(kref, struct host1x_channel, refcount);
> + struct host1x *host = dev_get_drvdata(channel->dev->parent);
> + struct host1x_channel_list *chlist = &host->channel_list;
>
> - if (channel->refcount == 1) {
> - struct host1x *host = dev_get_drvdata(channel->dev->parent);
> + host1x_hw_cdma_stop(host, &channel->cdma);
> + host1x_cdma_deinit(&channel->cdma);
>
> - host1x_hw_cdma_stop(host, &channel->cdma);
> - host1x_cdma_deinit(&channel->cdma);
> - }
> + clear_bit(channel->id, chlist->allocated_channels);
>
> - channel->refcount--;
> + up(&chlist->alloc_sema);
> +}
>
> - mutex_unlock(&channel->reflock);
> +void host1x_channel_put(struct host1x_channel *channel)
> +{
> + kref_put(&channel->refcount, release_channel);
> }
> EXPORT_SYMBOL(host1x_channel_put);
>
> +/**
> + * host1x_channel_request() - Allocate a channel
> + * @device: Host1x unit this channel will be used to send commands to
> + *
> + * Allocates a new host1x channel for @device. If there are no free channels,
> + * this will sleep until one becomes available. May return NULL if CDMA
> + * initialization fails.
> + */
> struct host1x_channel *host1x_channel_request(struct device *dev)
> {
> struct host1x *host = dev_get_drvdata(dev->parent);
> + struct host1x_channel_list *chlist = &host->channel_list;
> unsigned int max_channels = host->info->nb_channels;
> struct host1x_channel *channel = NULL;
> - unsigned long index;
> + unsigned int index;
> int err;
>
> - mutex_lock(&host->chlist_mutex);
> + down(&chlist->alloc_sema);
> +
It's a bit hard to follow lockings in the code, could you please explain why
you've added this semaphore? What problem it solves?
> + mutex_lock(&chlist->alloc_lock);
>
> - index = find_first_zero_bit(&host->allocated_channels, max_channels);
> - if (index >= max_channels)
> - goto fail;
> + index = find_first_zero_bit(chlist->allocated_channels, max_channels);
> + if (index >= max_channels) {
> + mutex_unlock(&chlist->alloc_lock);
> + dev_err(dev, "failed to find free channel\n");
> + return NULL;
> + }
>
> - channel = kzalloc(sizeof(*channel), GFP_KERNEL);
> - if (!channel)
> - goto fail;
> + set_bit(index, chlist->allocated_channels);
>
> - err = host1x_hw_channel_init(host, channel, index);
> - if (err < 0)
> - goto fail;
> + mutex_unlock(&chlist->alloc_lock);
>
> - /* Link device to host1x_channel */
> + channel = &chlist->channels[index];
> +
> + kref_init(&channel->refcount);
> + mutex_init(&channel->submit_lock);
> + channel->id = index;
> channel->dev = dev;
>
> - /* Add to channel list */
> - list_add_tail(&channel->list, &host->chlist.list);
> + err = host1x_hw_channel_init(host, channel, index);
> + if (err < 0)
> + goto free;
>
> - host->allocated_channels |= BIT(index);
> + err = host1x_cdma_init(&channel->cdma);
> + if (err < 0)
> + goto free;
>
> - mutex_unlock(&host->chlist_mutex);
> return channel;
>
> -fail:
> - dev_err(dev, "failed to init channel\n");
> - kfree(channel);
> - mutex_unlock(&host->chlist_mutex);
> - return NULL;
> -}
> -EXPORT_SYMBOL(host1x_channel_request);
> +free:
> + clear_bit(channel->id, chlist->allocated_channels);
> + up(&chlist->alloc_sema);
>
> -void host1x_channel_free(struct host1x_channel *channel)
> -{
> - struct host1x *host = dev_get_drvdata(channel->dev->parent);
> + dev_err(dev, "failed to initialize channel\n");
>
> - host->allocated_channels &= ~BIT(channel->id);
> - list_del(&channel->list);
> - kfree(channel);
> + return NULL;
> }
> -EXPORT_SYMBOL(host1x_channel_free);
> +EXPORT_SYMBOL(host1x_channel_request);
> diff --git a/drivers/gpu/host1x/channel.h b/drivers/gpu/host1x/channel.h
> index df767cf90d51..91a40f221415 100644
> --- a/drivers/gpu/host1x/channel.h
> +++ b/drivers/gpu/host1x/channel.h
> @@ -1,7 +1,7 @@
> /*
> * Tegra host1x Channel
> *
> - * Copyright (c) 2010-2013, NVIDIA Corporation.
> + * Copyright (c) 2010-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms and conditions of the GNU General Public License,
> @@ -20,27 +20,37 @@
> #define __HOST1X_CHANNEL_H
>
> #include <linux/io.h>
> +#include <linux/kref.h>
>
> #include "cdma.h"
>
> struct host1x;
> +struct host1x_channel;
> +
> +struct host1x_channel_list {
> + struct host1x_channel *channels;
> +
> + /* Allows clients to wait for a free channel */
> + struct semaphore alloc_sema;
> + struct mutex alloc_lock;
> + unsigned long *allocated_channels;
> +};
>
> struct host1x_channel {
> - struct list_head list;
> + struct kref refcount;
>
> - unsigned int refcount;
> unsigned int id;
> - struct mutex reflock;
> - struct mutex submitlock;
> + struct mutex submit_lock;
> void __iomem *regs;
> struct device *dev;
> struct host1x_cdma cdma;
> };
>
> /* channel list operations */
> -int host1x_channel_list_init(struct host1x *host);
> -
> -#define host1x_for_each_channel(host, channel)
> \
> - list_for_each_entry(channel, &host->chlist.list, list)
> +int host1x_channel_list_init(struct host1x_channel_list *chlist,
> + unsigned int num_channels);
> +void host1x_channel_list_free(struct host1x_channel_list *chlist);
> +struct host1x_channel *host1x_channel_get_index(struct host1x *host,
> + unsigned int index);
>
> #endif
> diff --git a/drivers/gpu/host1x/debug.c b/drivers/gpu/host1x/debug.c
> index d9330fcc62ad..0e8b66fea29f 100644
> --- a/drivers/gpu/host1x/debug.c
> +++ b/drivers/gpu/host1x/debug.c
> @@ -2,7 +2,7 @@
> * Copyright (C) 2010 Google, Inc.
> * Author: Erik Gilling <[email protected]>
> *
> - * Copyright (C) 2011-2013 NVIDIA Corporation
> + * Copyright (C) 2011-2017 NVIDIA Corporation
> *
> * This software is licensed under the terms of the GNU General Public
> * License version 2, as published by the Free Software Foundation, and
> @@ -43,24 +43,19 @@ void host1x_debug_output(struct output *o, const char
> *fmt, ...)
> o->fn(o->ctx, o->buf, len);
> }
>
> -static int show_channels(struct host1x_channel *ch, void *data, bool
> show_fifo)
> +static int show_channel(struct host1x_channel *ch, void *data, bool
> show_fifo)
> {
> struct host1x *m = dev_get_drvdata(ch->dev->parent);
> struct output *o = data;
>
> - mutex_lock(&ch->reflock);
> + mutex_lock(&ch->cdma.lock);
>
> - if (ch->refcount) {
> - mutex_lock(&ch->cdma.lock);
> + if (show_fifo)
> + host1x_hw_show_channel_fifo(m, ch, o);
>
> - if (show_fifo)
> - host1x_hw_show_channel_fifo(m, ch, o);
> + host1x_hw_show_channel_cdma(m, ch, o);
>
> - host1x_hw_show_channel_cdma(m, ch, o);
> - mutex_unlock(&ch->cdma.lock);
> - }
> -
> - mutex_unlock(&ch->reflock);
> + mutex_unlock(&ch->cdma.lock);
>
> return 0;
> }
> @@ -94,28 +89,22 @@ static void show_syncpts(struct host1x *m, struct output
> *o)
> host1x_debug_output(o, "\n");
> }
>
> -static void show_all(struct host1x *m, struct output *o)
> +static void show_all(struct host1x *m, struct output *o, bool show_fifo)
> {
> - struct host1x_channel *ch;
> + int i;
>
> host1x_hw_show_mlocks(m, o);
> show_syncpts(m, o);
> host1x_debug_output(o, "---- channels ----\n");
>
> - host1x_for_each_channel(m, ch)
> - show_channels(ch, o, true);
> -}
> -
> -static void show_all_no_fifo(struct host1x *host1x, struct output *o)
> -{
> - struct host1x_channel *ch;
> -
> - host1x_hw_show_mlocks(host1x, o);
> - show_syncpts(host1x, o);
> - host1x_debug_output(o, "---- channels ----\n");
> + for (i = 0; i < m->info->nb_channels; ++i) {
> + struct host1x_channel *ch = host1x_channel_get_index(m, i);
>
> - host1x_for_each_channel(host1x, ch)
> - show_channels(ch, o, false);
> + if (ch) {
> + show_channel(ch, o, show_fifo);
> + host1x_channel_put(ch);
> + }
> + }
> }
>
> static int host1x_debug_show_all(struct seq_file *s, void *unused)
> @@ -125,7 +114,7 @@ static int host1x_debug_show_all(struct seq_file *s, void
> *unused)
> .ctx = s
> };
>
> - show_all(s->private, &o);
> + show_all(s->private, &o, true);
>
> return 0;
> }
> @@ -137,7 +126,7 @@ static int host1x_debug_show(struct seq_file *s, void
> *unused)
> .ctx = s
> };
>
> - show_all_no_fifo(s->private, &o);
> + show_all(s->private, &o, false);
>
> return 0;
> }
> @@ -216,7 +205,7 @@ void host1x_debug_dump(struct host1x *host1x)
> .fn = write_to_printk
> };
>
> - show_all(host1x, &o);
> + show_all(host1x, &o, true);
> }
>
> void host1x_debug_dump_syncpts(struct host1x *host1x)
> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
> index a8234bb49403..f57ef45f75c9 100644
> --- a/drivers/gpu/host1x/dev.c
> +++ b/drivers/gpu/host1x/dev.c
> @@ -1,7 +1,7 @@
> /*
> * Tegra host1x driver
> *
> - * Copyright (c) 2010-2013, NVIDIA Corporation.
> + * Copyright (c) 2010-2017, NVIDIA Corporation.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms and conditions of the GNU General Public License,
> @@ -189,7 +189,8 @@ static int host1x_probe(struct platform_device *pdev)
> host->iova_end = geometry->aperture_end;
> }
>
> - err = host1x_channel_list_init(host);
> + err = host1x_channel_list_init(&host->channel_list,
> + host->info->nb_channels);
> if (err) {
> dev_err(&pdev->dev, "failed to initialize channel list\n");
> goto fail_detach_device;
> @@ -247,6 +248,7 @@ static int host1x_remove(struct platform_device *pdev)
> host1x_intr_deinit(host);
> host1x_syncpt_deinit(host);
> clk_disable_unprepare(host->clk);
> + host1x_channel_list_free(&host->channel_list);
>
> if (host->domain) {
> put_iova_domain(&host->iova);
> diff --git a/drivers/gpu/host1x/dev.h b/drivers/gpu/host1x/dev.h
> index 1ee79dbd1882..a558e39bf7f5 100644
> --- a/drivers/gpu/host1x/dev.h
> +++ b/drivers/gpu/host1x/dev.h
> @@ -1,5 +1,5 @@
> /*
> - * Copyright (C) 2012-2016 NVIDIA CORPORATION. All rights reserved.
> + * Copyright (C) 2012-2017 NVIDIA CORPORATION. All rights reserved.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms and conditions of the GNU General Public License,
> @@ -130,10 +130,8 @@ struct host1x {
> struct host1x_syncpt *nop_sp;
>
> struct mutex syncpt_mutex;
> - struct mutex chlist_mutex;
> - struct host1x_channel chlist;
> - unsigned long allocated_channels;
> - unsigned int num_allocated_channels;
> +
> + struct host1x_channel_list channel_list;
>
> struct dentry *debugfs;
>
> diff --git a/drivers/gpu/host1x/hw/channel_hw.c
> b/drivers/gpu/host1x/hw/channel_hw.c
> index 27dc78f4c400..286c81aad308 100644
> --- a/drivers/gpu/host1x/hw/channel_hw.c
> +++ b/drivers/gpu/host1x/hw/channel_hw.c
> @@ -138,13 +138,13 @@ static int channel_submit(struct host1x_job *job)
> }
>
> /* get submit lock */
> - err = mutex_lock_interruptible(&ch->submitlock);
> + err = mutex_lock_interruptible(&ch->submit_lock);
> if (err)
> goto error;
>
> completed_waiter = kzalloc(sizeof(*completed_waiter), GFP_KERNEL);
> if (!completed_waiter) {
> - mutex_unlock(&ch->submitlock);
> + mutex_unlock(&ch->submit_lock);
> err = -ENOMEM;
> goto error;
> }
> @@ -152,7 +152,7 @@ static int channel_submit(struct host1x_job *job)
> /* begin a CDMA submit */
> err = host1x_cdma_begin(&ch->cdma, job);
> if (err) {
> - mutex_unlock(&ch->submitlock);
> + mutex_unlock(&ch->submit_lock);
> goto error;
> }
>
> @@ -190,7 +190,7 @@ static int channel_submit(struct host1x_job *job)
> completed_waiter = NULL;
> WARN(err, "Failed to set submit complete interrupt");
>
> - mutex_unlock(&ch->submitlock);
> + mutex_unlock(&ch->submit_lock);
>
> return 0;
>
> @@ -202,10 +202,6 @@ static int channel_submit(struct host1x_job *job)
> static int host1x_channel_init(struct host1x_channel *ch, struct host1x *dev,
> unsigned int index)
> {
> - ch->id = index;
> - mutex_init(&ch->reflock);
> - mutex_init(&ch->submitlock);
> -
> ch->regs = dev->regs + index * HOST1X_CHANNEL_SIZE;
> return 0;
> }
> diff --git a/include/linux/host1x.h b/include/linux/host1x.h
> index fd9b526486e0..921ec6465952 100644
> --- a/include/linux/host1x.h
> +++ b/include/linux/host1x.h
> @@ -157,7 +157,6 @@ struct host1x_channel;
> struct host1x_job;
>
> struct host1x_channel *host1x_channel_request(struct device *dev);
> -void host1x_channel_free(struct host1x_channel *channel);
> struct host1x_channel *host1x_channel_get(struct host1x_channel *channel);
> void host1x_channel_put(struct host1x_channel *channel);
> int host1x_job_submit(struct host1x_job *job);
>
--
Dmitry
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