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9d0aa601e4
linux/drivers/video/fbdev
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Mikulas Patocka 9d0aa601e4 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 <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
[b.zolnierkie: fix immediatelly -> immediately typo]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2018-07-25 15:41:54 +02:00
..
aty video: fbdev: aty: radeon_pm: Replace mdelay with msleep in radeonfb_pci_suspend 2018-04-24 18:11:21 +02:00
core fb: fix lost console when the user unplugs a USB adapter 2018-07-25 15:41:54 +02:00
geode x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping 2018-02-15 01:15:52 +01:00
i810 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
intelfb video: fbdev: intelfb: deprecate pci_get_bus_and_slot() 2018-01-17 08:16:46 -06:00
kyro video: fbdev: kyro: constify pci_device_id. 2017-08-01 17:20:42 +02:00
matrox video: matroxfb: Delete an error message for a failed memory allocation in matroxfb_crtc2_probe() 2018-03-28 16:34:28 +02:00
mb862xx treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
mbx License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mmp fbdev changes for v4.18: 2018-06-17 05:00:24 +09:00
nvidia fbdev changes for v4.18: 2018-06-17 05:00:24 +09:00
omap fbdev: omapfb: off by one in omapfb_register_client() 2018-07-24 19:11:28 +02:00
omap2 fbdev: fix omap2/omapfb/dss/ indentation warning 2018-07-24 19:11:28 +02:00
riva treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
savage video: fbdev: savage: Replace mdelay with usleep_range in savage_init_hw 2018-04-24 18:11:21 +02:00
sis video: fbdev: sis: avoid mismatched prototypes 2018-03-12 17:06:52 +01:00
vermilion video: fbdev: vermilion: use 64-bit arithmetic instead of 32-bit 2018-03-12 17:06:54 +01:00
via video: fbdev: mark expected switch fall-throughs 2018-07-24 19:11:28 +02:00
68328fb.c video: fbdev: annotate fb_fix_screeninfo with const and __initconst 2017-09-04 16:00:49 +02:00
acornfb.c drivers/video/fbdev: Fixing coding guidelines in acornfb.c 2017-04-07 17:03:24 +02:00
acornfb.h
amba-clcd-nomadik.c fbdev changes for v4.11: 2017-02-25 13:20:22 -08:00
amba-clcd-nomadik.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
amba-clcd-versatile.c video: ARM CLCD: use panel device node for panel initialization 2017-01-30 17:39:48 +01:00
amba-clcd-versatile.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
amba-clcd.c video: ARM CLCD: Improve a size determination in clcdfb_probe() 2018-03-28 16:34:29 +02:00
amifb.c video: fbdev: amifb: remove impossible condition 2017-02-08 16:44:00 +01:00
arcfb.c Annotate hardware config module parameters in drivers/video/ 2017-04-20 12:02:32 +01:00
arkfb.c video: fbdev: arkfb: constify pci_device_id. 2017-08-01 17:20:42 +02:00
asiliantfb.c video: fbdev: asiliantfb: constify pci_device_id. 2017-08-01 17:20:41 +02:00
atafb_iplan2p2.c
atafb_iplan2p4.c
atafb_iplan2p8.c
atafb_mfb.c
atafb_utils.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
atafb.c
atafb.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
atmel_lcdfb.c video: fbdev: atmel_lcdfb: convert to use GPIO descriptors 2018-03-12 17:06:52 +01:00
au1100fb.c fbdev changes for v4.18: 2018-06-17 05:00:24 +09:00
au1100fb.h
au1200fb.c video: fbdev: fix spelling mistake: "frambuffer" -> "framebuffer" 2018-05-15 12:41:11 +02:00
au1200fb.h fbdev: au1200fb: delete duplicate header contents 2018-01-04 16:53:49 +01:00
broadsheetfb.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
bt431.h
bt455.h
bw2.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
c2p_core.h
c2p_iplan2.c
c2p_planar.c
c2p.h
carminefb_regs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
carminefb.c
carminefb.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cg3.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
cg6.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
cg14.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
chipsfb.c video/chips: constify fb_fix_screeninfo and fb_var_screeninfo structures 2017-08-01 17:20:39 +02:00
cirrusfb.c video: fbdev: cirrusfb: mark expected switch fall-throughs 2017-11-09 18:09:32 +01:00
clps711x-fb.c video: clps711x-fb: Changing the compatibility string to match with the smallest supported chip 2016-07-06 17:38:19 +02:00
clps711xfb.c
cobalt_lcdfb.c video: cobalt_lcdfb: constify fb_fix_screeninfo structure 2017-08-01 17:20:39 +02:00
controlfb.c
controlfb.h fbdev: controlfb: Add missing modes to fix out of bounds access 2017-11-09 18:09:33 +01:00
cyber2000fb.c video: fbdev: make fb_videomode const 2017-09-04 16:00:49 +02:00
cyber2000fb.h
da8xx-fb.c fbdev: da8xx-fb: Drop unnecessary static 2017-08-01 17:20:39 +02:00
dnfb.c video/fbdev/dnfb: Use common error handling code in dnfb_probe() 2017-11-09 18:09:31 +01:00
edid.h
efifb.c efifb: BGRT: Do not copy the boot graphics for non native resolutions 2018-07-24 19:11:28 +02:00
ep93xx-fb.c
fb-puv3.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
ffb.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
fm2fb.c video: fm2fb: constify zorro_device_id 2017-09-04 16:00:49 +02:00
fsl-diu-fb.c video: fbdev: fsl-diu-fb: Remove VLA usage 2018-07-24 19:11:26 +02:00
g364fb.c
gbefb.c
goldfishfb.c video: goldfishfb: fix memory leak on driver remove 2018-07-24 19:11:27 +02:00
grvga.c video: fbdev: annotate fb_fix_screeninfo with const and __initconst 2017-09-04 16:00:49 +02:00
gxt4500.c
hecubafb.c video: fbdev: constify fb_fix_screeninfo and fb_var_screeninfo structures 2016-09-27 11:16:35 +03:00
hgafb.c video: fbdev: constify fb_fix_screeninfo and fb_var_screeninfo structures 2016-09-27 11:16:35 +03:00
hitfb.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hpfb.c hpfb: use probe_kernel_read() 2017-05-27 15:41:17 -04:00
hyperv_fb.c
i740_reg.h
i740fb.c video: fbdev: mark expected switch fall-throughs 2018-07-24 19:11:28 +02:00
imsttfb.c video: fbdev: imsttfb: constify pci_device_id. 2017-08-01 17:20:43 +02:00
imxfb.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
jz4740_fb.c fbdev: jz4740-fb: Let the pinctrl driver configure the pins 2017-05-22 17:22:06 +02:00
Kconfig video: fbdev: via: allow COMPILE_TEST build 2018-05-15 12:41:10 +02:00
leo.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
macfb.c nubus: Adopt standard linked list implementation 2018-01-16 16:47:29 +01:00
macmodes.c
macmodes.h
Makefile video: fbdev: remove unused sh_mobile_meram driver 2018-05-14 15:47:30 +02:00
maxinefb.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
metronomefb.c video: fbdev: metronomefb: fix some off by one bugs 2018-07-24 19:11:26 +02:00
mx3fb.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mxsfb.c treewide: devm_kzalloc() -> devm_kcalloc() 2018-06-12 16:19:22 -07:00
n411.c Annotate hardware config module parameters in drivers/video/ 2017-04-20 12:02:32 +01:00
neofb.c video: fbdev: neofb: constify pci_device_id. 2017-08-01 17:20:44 +02:00
nuc900fb.c
nuc900fb.h
ocfb.c
offb.c video: offb: Deallocate the color map 2018-03-12 17:06:54 +01:00
p9100.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
platinumfb.c
platinumfb.h
pm2fb.c video: fbdev: mark expected switch fall-throughs 2018-07-24 19:11:28 +02:00
pm3fb.c video: fbdev: pm3fb: constify pci_device_id. 2017-08-01 17:20:45 +02:00
pmag-aa-fb.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
pmag-ba-fb.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
pmagb-b-fb.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
ps3fb.c video: fbdev: annotate fb_fix_screeninfo with const and __initconst 2017-09-04 16:00:49 +02:00
pvr2fb.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
pxa3xx-gcu.c video: fbdev: pxa3xx_gcu: add devicetree bindings 2018-07-24 19:11:25 +02:00
pxa3xx-gcu.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pxa168fb.c
pxa168fb.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pxafb.c video: fbdev: pxafb: Add support for lcd-supply regulator 2018-07-24 19:11:26 +02:00
pxafb.h video: fbdev: pxafb: Add support for lcd-supply regulator 2018-07-24 19:11:26 +02:00
q40fb.c video: fbdev: make fb_var_screeninfo const 2017-09-04 16:00:50 +02:00
s1d13xxxfb.c fbdev: s1d13xxxfb: remove m32r specific hacks 2018-03-26 15:56:46 +02:00
s3c2410fb.c video: s3c2410fb: Register cpufreq notifier only on S3C24xx 2016-08-11 17:54:55 +03:00
s3c2410fb.h video: s3c2410fb: Register cpufreq notifier only on S3C24xx 2016-08-11 17:54:55 +03:00
s3c-fb.c video: fbdev: s3c-fb: remove dead platform code for Exynos and S5PV210 platforms 2018-03-28 16:34:29 +02:00
s3fb.c video: fbdev: s3fb: constify pci_device_id. 2017-08-01 17:20:45 +02:00
sa1100fb.c video: sa1100fb: move pseudo palette into sa1100fb_info structure 2017-10-17 16:01:13 +02:00
sa1100fb.h video: sa1100fb: move pseudo palette into sa1100fb_info structure 2017-10-17 16:01:13 +02:00
sbuslib.c fbdev: Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper(). 2018-03-07 14:00:34 +01:00
sbuslib.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sh7760fb.c
sh_mobile_lcdcfb.c video: fbdev: sh_mobile_lcdcfb: remove unused MERAM support 2018-05-14 15:47:30 +02:00
sh_mobile_lcdcfb.h video: fbdev: sh_mobile_lcdcfb: remove unused MERAM support 2018-05-14 15:47:30 +02:00
simplefb.c video: fbdev: simplefb: Stop including <linux/clk-provider.h> 2018-07-03 17:43:09 +02:00
skeletonfb.c docs: fix broken references with multiple hints 2018-06-15 18:10:01 -03:00
sm501fb.c video: sm501fb: Improve a size determination in sm501fb_probe() 2018-04-26 12:24:18 +02:00
sm712.h
sm712fb.c video: fbdev: sm712fb.c: fixed constant-left comparison warning 2017-08-01 17:20:38 +02:00
smscufx.c video: smscufx: Delete an error message for a failed memory allocation in ufx_realloc_framebuffer() 2018-03-28 16:34:28 +02:00
ssd1307fb.c video: ssd1307fb: Improve a size determination in ssd1307fb_probe() 2018-03-28 16:34:28 +02:00
sstfb.c
sticore.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stifb.c fbdev changes for v4.17: 2018-04-10 10:20:00 -07:00
sunxvr500.c video: fbdev: sunxvr500: constify pci_device_id. 2017-08-01 17:20:43 +02:00
sunxvr1000.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
sunxvr2500.c video: fbdev: sunxvr2500: constify pci_device_id. 2017-08-01 17:20:41 +02:00
tcx.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
tdfxfb.c video: fbdev: mark expected switch fall-throughs 2018-07-24 19:11:28 +02:00
tgafb.c
tmiofb.c
tridentfb.c video: fbdev: tridentfb: remove deadcode on unreachable case statement 2018-07-24 19:11:28 +02:00
udlfb.c udlfb: fix semaphore value leak 2018-07-25 15:41:54 +02:00
uvesafb.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
valkyriefb.c
valkyriefb.h
vesafb.c
vfb.c vfb: fix video mode and line_length being set when loaded 2018-01-04 16:53:50 +01:00
vga16fb.c video: fbdev: remove redundant self assignment of 'height' 2017-12-29 19:48:43 +01:00
vt8500lcdfb.c video/fbdev/vt8500lcdfb: Delete an error message for a failed memory allocation in vt8500lcd_probe() 2017-12-29 19:48:44 +01:00
vt8500lcdfb.h
vt8623fb.c video: fbdev: vt8623fb: constify vt8623_timing_regs 2017-08-18 19:56:40 +02:00
w100fb.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
w100fb.h
wm8505fb_regs.h
wm8505fb.c video/fbdev/wm8505fb: Delete an error message for a failed memory allocation in wm8505fb_probe() 2017-12-29 19:48:43 +01:00
wmt_ge_rops.c
wmt_ge_rops.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xen-fbfront.c treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
xilinxfb.c video: fbdev: Fix multiple style issues in xilinxfb 2017-08-21 16:49:57 +02:00