From 9d0aa601e4cd9c0892f90d36e8488d79b72f4073 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:54 +0200 Subject: udlfb: fix semaphore value leak I observed that the performance of the udl fb driver degrades over time. On a freshly booted machine, it takes 6 seconds to do "ls -la /usr/bin"; after some time of use, the same operation takes 14 seconds. The reason is that the value of "limit_sem" decays over time. The udl driver uses a semaphore "limit_set" to specify how many free urbs are there on dlfb->urbs.list. If the count is zero, the "down" operation will sleep until some urbs are added to the freelist. In order to avoid some hypothetical deadlock, the driver will not call "up" immediately, but it will offload it to a workqueue. The problem is that if we call "schedule_delayed_work" on the same work item multiple times, the work item may only be executed once. This is happening: * some urb completes * dlfb_urb_completion adds it to the free list * dlfb_urb_completion calls schedule_delayed_work to schedule the function dlfb_release_urb_work to increase the semaphore count * as the urb is on the free list, some other task grabs it and submits it * the submitted urb completes, dlfb_urb_completion is called again * dlfb_urb_completion calls schedule_delayed_work, but the work is already scheduled, so it does nothing * finally, dlfb_release_urb_work is called, it increases the semaphore count by 1, although it should increase it by 2 So, the semaphore count is decreasing over time, and this causes gradual performance degradation. Note that in the current kernel, the "up" function may be called from interrupt and it may race with the "down" function called by another thread, so we don't have to offload the call of "up" to a workqueue at all. This patch removes the workqueue code. The patch also changes "down_interruptible" to "down" in dlfb_free_urb_list, so that we will clean up the driver properly even if a signal arrives. With this patch, the performance of udlfb no longer degrades. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org [b.zolnierkie: fix immediatelly -> immediately typo] Signed-off-by: Bartlomiej Zolnierkiewicz --- include/video/udlfb.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/video') diff --git a/include/video/udlfb.h b/include/video/udlfb.h index 0cabe6b09095..8a1948f3c07f 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -20,7 +20,6 @@ struct dloarea { struct urb_node { struct list_head entry; struct dlfb_data *dlfb; - struct delayed_work release_urb_work; struct urb *urb; }; -- cgit v1.2.3 From 564f1807379298dfdb12ed0d5b25fcb89c238527 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:55 +0200 Subject: udlfb: don't switch if we are switching to the same videomode The udlfb driver reprograms the hardware everytime the user switches the console, that makes quite unusable when working on the console. This patch makes the driver remember the videomode we are in and avoid reprogramming the hardware if we switch to the same videomode. We mask the "activate" field and the "FB_VMODE_SMOOTH_XPAN" flag when comparing the videomode, because they cause spurious switches when switching to and from the Xserver. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Bartlomiej Zolnierkiewicz --- drivers/video/fbdev/udlfb.c | 18 ++++++++++++++++-- include/video/udlfb.h | 1 + 2 files changed, 17 insertions(+), 2 deletions(-) (limited to 'include/video') diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c index 864e2917c276..fa63a2e359d6 100644 --- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -1041,10 +1041,24 @@ static int dlfb_ops_set_par(struct fb_info *info) int result; u16 *pix_framebuffer; int i; + struct fb_var_screeninfo fvs; + + /* clear the activate field because it causes spurious miscompares */ + fvs = info->var; + fvs.activate = 0; + fvs.vmode &= ~FB_VMODE_SMOOTH_XPAN; + + if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo))) + return 0; result = dlfb_set_video_mode(dlfb, &info->var); - if ((result == 0) && (dlfb->fb_count == 0)) { + if (result) + return result; + + dlfb->current_mode = fvs; + + if (dlfb->fb_count == 0) { /* paint greenscreen */ @@ -1056,7 +1070,7 @@ static int dlfb_ops_set_par(struct fb_info *info) info->screen_base); } - return result; + return 0; } /* To fonzi the jukebox (e.g. make blanking changes take effect) */ diff --git a/include/video/udlfb.h b/include/video/udlfb.h index 8a1948f3c07f..bc2e9cf34aa5 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -56,6 +56,7 @@ struct dlfb_data { atomic_t bytes_identical; /* saved effort with backbuffer comparison */ atomic_t bytes_sent; /* to usb, after compression including overhead */ atomic_t cpu_kcycles_used; /* transpired during pixel processing */ + struct fb_var_screeninfo current_mode; }; #define NR_USB_REQUEST_I2C_SUB_IO 0x02 -- cgit v1.2.3 From 2c29cfc3eaf11779176bf41475cfca49bccba11c Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:55 +0200 Subject: udlfb: make a local copy of fb_ops The defio subsystem overwrites the method fb_osp->mmap. That method is stored in module's static data - and that means that if we have multiple diplaylink adapters, they will over write each other's method. In order to avoid interference between multiple adapters, we copy the fb_ops structure to a device-local memory. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Bartlomiej Zolnierkiewicz --- drivers/video/fbdev/udlfb.c | 3 ++- include/video/udlfb.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'include/video') diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c index fa63a2e359d6..770c1c8cfbd0 100644 --- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -1665,7 +1665,8 @@ static void dlfb_init_framebuffer_work(struct work_struct *work) dlfb->info = info; info->par = dlfb; info->pseudo_palette = dlfb->pseudo_palette; - info->fbops = &dlfb_ops; + dlfb->ops = dlfb_ops; + info->fbops = &dlfb->ops; retval = fb_alloc_cmap(&info->cmap, 256, 0); if (retval < 0) { diff --git a/include/video/udlfb.h b/include/video/udlfb.h index bc2e9cf34aa5..b4f43d3ac1af 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -51,6 +51,7 @@ struct dlfb_data { int base8; u32 pseudo_palette[256]; int blank_mode; /*one of FB_BLANK_ */ + struct fb_ops ops; /* blit-only rendering path metrics, exposed through sysfs */ atomic_t bytes_rendered; /* raw pixel-bytes driver asked to render */ atomic_t bytes_identical; /* saved effort with backbuffer comparison */ -- cgit v1.2.3 From bb24153a3f13dd0dbc1f8055ad97fe346d598f66 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:55 +0200 Subject: udlfb: set optimal write delay The default delay 5 jiffies is too much when the kernel is compiled with HZ=100 - it results in jumpy cursor in Xwindow. In order to find out the optimal delay, I benchmarked the driver on 1280x720x30fps video. I found out that with HZ=1000, 10ms is acceptable, but with HZ=250 or HZ=300, we need 4ms, so that the video is played without any frame skips. This patch changes the delay to this value. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Bartlomiej Zolnierkiewicz --- include/video/udlfb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/video') diff --git a/include/video/udlfb.h b/include/video/udlfb.h index b4f43d3ac1af..6e1a2e790b1b 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -88,7 +88,7 @@ struct dlfb_data { #define MIN_RAW_PIX_BYTES 2 #define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES) -#define DL_DEFIO_WRITE_DELAY 5 /* fb_deferred_io.delay in jiffies */ +#define DL_DEFIO_WRITE_DELAY msecs_to_jiffies(HZ <= 300 ? 4 : 10) /* optimal value for 720p video */ #define DL_DEFIO_WRITE_DISABLE (HZ*60) /* "disable" with long delay */ /* remove these once align.h patch is taken into kernel */ -- cgit v1.2.3 From 7433914efd584b22bb49d3e1eee001f5d0525ecd Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 25 Jul 2018 15:41:56 +0200 Subject: udlfb: allow reallocating the framebuffer This patch changes udlfb so that it may reallocate the framebuffer when setting higher-resolution mode. If we boot the system without monitor attached, udlfb creates a framebuffer with the size 800x600. This patch makes it possible to select higher videomode with the fbset command when a monitor is attached. Note that there is no reliable way to prevent the system from touching the old framebuffer, so we must not free it. We add it to the list dlfb->deferred_free and free it when the driver is unloaded. Signed-off-by: Mikulas Patocka [b.zolnierkie: sparse fixes] Signed-off-by: Bartlomiej Zolnierkiewicz --- drivers/video/fbdev/udlfb.c | 74 ++++++++++++++++++++++++++++++--------------- include/video/udlfb.h | 1 + 2 files changed, 50 insertions(+), 25 deletions(-) (limited to 'include/video') diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c index 862e8027acf6..bdca60f92098 100644 --- a/drivers/video/fbdev/udlfb.c +++ b/drivers/video/fbdev/udlfb.c @@ -73,6 +73,13 @@ static bool fb_defio = 1; /* Detect mmap writes using page faults */ static bool shadow = 1; /* Optionally disable shadow framebuffer */ static int pixel_limit; /* Optionally force a pixel resolution limit */ +struct dlfb_deferred_free { + struct list_head list; + void *mem; +}; + +static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len); + /* dlfb keeps a list of urbs for efficient bulk transfers */ static void dlfb_urb_completion(struct urb *urb); static struct urb *dlfb_get_urb(struct dlfb_data *dlfb); @@ -927,6 +934,12 @@ static void dlfb_free(struct kref *kref) { struct dlfb_data *dlfb = container_of(kref, struct dlfb_data, kref); + while (!list_empty(&dlfb->deferred_free)) { + struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list); + list_del(&d->list); + vfree(d->mem); + kfree(d); + } vfree(dlfb->backing_buffer); kfree(dlfb->edid); kfree(dlfb); @@ -1020,10 +1033,6 @@ static int dlfb_ops_check_var(struct fb_var_screeninfo *var, struct fb_videomode mode; struct dlfb_data *dlfb = info->par; - /* TODO: support dynamically changing framebuffer size */ - if ((var->xres * var->yres * 2) > info->fix.smem_len) - return -EINVAL; - /* set device-specific elements of var unrelated to mode */ dlfb_var_color_format(var); @@ -1042,6 +1051,7 @@ static int dlfb_ops_set_par(struct fb_info *info) u16 *pix_framebuffer; int i; struct fb_var_screeninfo fvs; + u32 line_length = info->var.xres * (info->var.bits_per_pixel / 8); /* clear the activate field because it causes spurious miscompares */ fvs = info->var; @@ -1051,13 +1061,17 @@ static int dlfb_ops_set_par(struct fb_info *info) if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo))) return 0; + result = dlfb_realloc_framebuffer(dlfb, info, info->var.yres * line_length); + if (result) + return result; + result = dlfb_set_video_mode(dlfb, &info->var); if (result) return result; dlfb->current_mode = fvs; - info->fix.line_length = info->var.xres * (info->var.bits_per_pixel / 8); + info->fix.line_length = line_length; if (dlfb->fb_count == 0) { @@ -1066,11 +1080,11 @@ static int dlfb_ops_set_par(struct fb_info *info) pix_framebuffer = (u16 *) info->screen_base; for (i = 0; i < info->fix.smem_len / 2; i++) pix_framebuffer[i] = 0x37e6; - - dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres, - info->screen_base); } + dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres, + info->screen_base); + return 0; } @@ -1146,21 +1160,29 @@ static struct fb_ops dlfb_ops = { }; +static void dlfb_deferred_vfree(struct dlfb_data *dlfb, void *mem) +{ + struct dlfb_deferred_free *d = kmalloc(sizeof(struct dlfb_deferred_free), GFP_KERNEL); + if (!d) + return; + d->mem = mem; + list_add(&d->list, &dlfb->deferred_free); +} + /* * Assumes &info->lock held by caller * Assumes no active clients have framebuffer open */ -static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info) +static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len) { - int old_len = info->fix.smem_len; - int new_len; - unsigned char *old_fb = info->screen_base; + u32 old_len = info->fix.smem_len; + const void *old_fb = (const void __force *)info->screen_base; unsigned char *new_fb; unsigned char *new_back = NULL; - new_len = info->fix.line_length * info->var.yres; + new_len = PAGE_ALIGN(new_len); - if (PAGE_ALIGN(new_len) > old_len) { + if (new_len > old_len) { /* * Alloc system memory for virtual framebuffer */ @@ -1169,14 +1191,15 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info dev_err(info->dev, "Virtual framebuffer alloc failed\n"); return -ENOMEM; } + memset(new_fb, 0xff, new_len); if (info->screen_base) { memcpy(new_fb, old_fb, old_len); - vfree(info->screen_base); + dlfb_deferred_vfree(dlfb, (void __force *)info->screen_base); } - info->screen_base = new_fb; - info->fix.smem_len = PAGE_ALIGN(new_len); + info->screen_base = (char __iomem *)new_fb; + info->fix.smem_len = new_len; info->fix.smem_start = (unsigned long) new_fb; info->flags = udlfb_info_flags; @@ -1192,7 +1215,7 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info dev_info(info->dev, "No shadow/backing buffer allocated\n"); else { - vfree(dlfb->backing_buffer); + dlfb_deferred_vfree(dlfb, dlfb->backing_buffer); dlfb->backing_buffer = new_back; } } @@ -1344,11 +1367,6 @@ static int dlfb_setup_modes(struct dlfb_data *dlfb, * with mode size info, we can now alloc our framebuffer. */ memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix)); - info->fix.line_length = info->var.xres * - (info->var.bits_per_pixel / 8); - - result = dlfb_realloc_framebuffer(dlfb, info); - } else result = -EINVAL; @@ -1436,7 +1454,10 @@ static ssize_t edid_store( if (!dlfb->edid || memcmp(src, dlfb->edid, src_size)) return -EINVAL; - dlfb_ops_set_par(fb_info); + ret = dlfb_ops_set_par(fb_info); + if (ret) + return ret; + return src_size; } @@ -1596,6 +1617,7 @@ static int dlfb_usb_probe(struct usb_interface *intf, } kref_init(&dlfb->kref); /* matching kref_put in usb .disconnect fn */ + INIT_LIST_HEAD(&dlfb->deferred_free); dlfb->udev = usbdev; usb_set_intfdata(intf, dlfb); @@ -1693,7 +1715,9 @@ static void dlfb_init_framebuffer_work(struct work_struct *work) dlfb_select_std_channel(dlfb); dlfb_ops_check_var(&info->var, info); - dlfb_ops_set_par(info); + retval = dlfb_ops_set_par(info); + if (retval) + goto error; retval = register_framebuffer(info); if (retval < 0) { diff --git a/include/video/udlfb.h b/include/video/udlfb.h index 6e1a2e790b1b..3abd327bada6 100644 --- a/include/video/udlfb.h +++ b/include/video/udlfb.h @@ -58,6 +58,7 @@ struct dlfb_data { atomic_t bytes_sent; /* to usb, after compression including overhead */ atomic_t cpu_kcycles_used; /* transpired during pixel processing */ struct fb_var_screeninfo current_mode; + struct list_head deferred_free; }; #define NR_USB_REQUEST_I2C_SUB_IO 0x02 -- cgit v1.2.3