diff options
| -rw-r--r-- | drivers/hwtracing/intel_th/msu.c | 92 |
1 files changed, 49 insertions, 43 deletions
diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c index 25af214..ee15306 100644 --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -122,7 +122,6 @@ struct msc { atomic_t mmap_count; struct mutex buf_mutex; - struct mutex iter_mutex; struct list_head iter_list; /* config */ @@ -257,23 +256,37 @@ static struct msc_iter *msc_iter_install(struct msc *msc) iter = kzalloc(sizeof(*iter), GFP_KERNEL); if (!iter) - return NULL; + return ERR_PTR(-ENOMEM); + + mutex_lock(&msc->buf_mutex); + + /* + * Reading and tracing are mutually exclusive; if msc is + * enabled, open() will fail; otherwise existing readers + * will prevent enabling the msc and the rest of fops don't + * need to worry about it. + */ + if (msc->enabled) { + kfree(iter); + iter = ERR_PTR(-EBUSY); + goto unlock; + } msc_iter_init(iter); iter->msc = msc; - mutex_lock(&msc->iter_mutex); list_add_tail(&iter->entry, &msc->iter_list); - mutex_unlock(&msc->iter_mutex); +unlock: + mutex_unlock(&msc->buf_mutex); return iter; } static void msc_iter_remove(struct msc_iter *iter, struct msc *msc) { - mutex_lock(&msc->iter_mutex); + mutex_lock(&msc->buf_mutex); list_del(&iter->entry); - mutex_unlock(&msc->iter_mutex); + mutex_unlock(&msc->buf_mutex); kfree(iter); } @@ -454,7 +467,6 @@ static void msc_buffer_clear_hw_header(struct msc *msc) { struct msc_window *win; - mutex_lock(&msc->buf_mutex); list_for_each_entry(win, &msc->win_list, entry) { unsigned int blk; size_t hw_sz = sizeof(struct msc_block_desc) - @@ -466,7 +478,6 @@ static void msc_buffer_clear_hw_header(struct msc *msc) memset(&bdesc->hw_tag, 0, hw_sz); } } - mutex_unlock(&msc->buf_mutex); } /** @@ -474,12 +485,15 @@ static void msc_buffer_clear_hw_header(struct msc *msc) * @msc: the MSC device to configure * * Program storage mode, wrapping, burst length and trace buffer address - * into a given MSC. If msc::enabled is set, enable the trace, too. + * into a given MSC. Then, enable tracing and set msc::enabled. + * The latter is serialized on msc::buf_mutex, so make sure to hold it. */ static int msc_configure(struct msc *msc) { u32 reg; + lockdep_assert_held(&msc->buf_mutex); + if (msc->mode > MSC_MODE_MULTI) return -ENOTSUPP; @@ -497,21 +511,19 @@ static int msc_configure(struct msc *msc) reg = ioread32(msc->reg_base + REG_MSU_MSC0CTL); reg &= ~(MSC_MODE | MSC_WRAPEN | MSC_EN | MSC_RD_HDR_OVRD); + reg |= MSC_EN; reg |= msc->mode << __ffs(MSC_MODE); reg |= msc->burst_len << __ffs(MSC_LEN); - /*if (msc->mode == MSC_MODE_MULTI) - reg |= MSC_RD_HDR_OVRD; */ + if (msc->wrap) reg |= MSC_WRAPEN; - if (msc->enabled) - reg |= MSC_EN; iowrite32(reg, msc->reg_base + REG_MSU_MSC0CTL); - if (msc->enabled) { - msc->thdev->output.multiblock = msc->mode == MSC_MODE_MULTI; - intel_th_trace_enable(msc->thdev); - } + msc->thdev->output.multiblock = msc->mode == MSC_MODE_MULTI; + intel_th_trace_enable(msc->thdev); + msc->enabled = 1; + return 0; } @@ -521,15 +533,14 @@ static int msc_configure(struct msc *msc) * @msc: MSC device to disable * * If @msc is enabled, disable tracing on the switch and then disable MSC - * storage. + * storage. Caller must hold msc::buf_mutex. */ static void msc_disable(struct msc *msc) { unsigned long count; u32 reg; - if (!msc->enabled) - return; + lockdep_assert_held(&msc->buf_mutex); intel_th_trace_disable(msc->thdev); @@ -569,33 +580,35 @@ static void msc_disable(struct msc *msc) static int intel_th_msc_activate(struct intel_th_device *thdev) { struct msc *msc = dev_get_drvdata(&thdev->dev); - int ret = 0; + int ret = -EBUSY; if (!atomic_inc_unless_negative(&msc->user_count)) return -ENODEV; - mutex_lock(&msc->iter_mutex); - if (!list_empty(&msc->iter_list)) - ret = -EBUSY; - mutex_unlock(&msc->iter_mutex); + mutex_lock(&msc->buf_mutex); - if (ret) { - atomic_dec(&msc->user_count); - return ret; - } + /* if there are readers, refuse */ + if (list_empty(&msc->iter_list)) + ret = msc_configure(msc); - msc->enabled = 1; + mutex_unlock(&msc->buf_mutex); + + if (ret) + atomic_dec(&msc->user_count); - return msc_configure(msc); + return ret; } static void intel_th_msc_deactivate(struct intel_th_device *thdev) { struct msc *msc = dev_get_drvdata(&thdev->dev); - msc_disable(msc); - - atomic_dec(&msc->user_count); + mutex_lock(&msc->buf_mutex); + if (msc->enabled) { + msc_disable(msc); + atomic_dec(&msc->user_count); + } + mutex_unlock(&msc->buf_mutex); } /** @@ -1035,8 +1048,8 @@ static int intel_th_msc_open(struct inode *inode, struct file *file) return -EPERM; iter = msc_iter_install(msc); - if (!iter) - return -ENOMEM; + if (IS_ERR(iter)) + return PTR_ERR(iter); file->private_data = iter; @@ -1101,11 +1114,6 @@ static ssize_t intel_th_msc_read(struct file *file, char __user *buf, if (!atomic_inc_unless_negative(&msc->user_count)) return 0; - if (msc->enabled) { - ret = -EBUSY; - goto put_count; - } - if (msc->mode == MSC_MODE_SINGLE && !msc->single_wrap) size = msc->single_sz; else @@ -1254,8 +1262,6 @@ static int intel_th_msc_init(struct msc *msc) msc->mode = MSC_MODE_MULTI; mutex_init(&msc->buf_mutex); INIT_LIST_HEAD(&msc->win_list); - - mutex_init(&msc->iter_mutex); INIT_LIST_HEAD(&msc->iter_list); msc->burst_len = |
