From 74071e2a739f96229cbc90a0ef7d93a496082422 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Sat, 16 Jul 2011 23:30:55 +1000 Subject: [PATCH] fb_set_suspend() must be called with the console semaphore held, which means the code path coming in here will first take the console_lock() and then call lock_fb_info(). MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit However several framebuffer ioctl commands acquire these locks in reverse order (lock_fb_info() and then console_lock()). This gives rise to potential AB-BA deadlock. Fix this by changing the order of acquisition in the ioctl commands that make use of console_lock(). Signed-off-by: Andrea Righi Reported-by: Peter Nordström (Palm GBU) Cc: Geert Uytterhoeven Cc: Signed-off-by: Andrew Morton --- drivers/video/fbmem.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index 5aac00eb1830..ee2c060b034d 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -1076,14 +1076,16 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, case FBIOPUT_VSCREENINFO: if (copy_from_user(&var, argp, sizeof(var))) return -EFAULT; - if (!lock_fb_info(info)) - return -ENODEV; console_lock(); + if (!lock_fb_info(info)) { + console_unlock(); + return -ENODEV; + } info->flags |= FBINFO_MISC_USEREVENT; ret = fb_set_var(info, &var); info->flags &= ~FBINFO_MISC_USEREVENT; - console_unlock(); unlock_fb_info(info); + console_unlock(); if (!ret && copy_to_user(argp, &var, sizeof(var))) ret = -EFAULT; break; @@ -1112,12 +1114,14 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, case FBIOPAN_DISPLAY: if (copy_from_user(&var, argp, sizeof(var))) return -EFAULT; - if (!lock_fb_info(info)) - return -ENODEV; console_lock(); + if (!lock_fb_info(info)) { + console_unlock(); + return -ENODEV; + } ret = fb_pan_display(info, &var); - console_unlock(); unlock_fb_info(info); + console_unlock(); if (ret == 0 && copy_to_user(argp, &var, sizeof(var))) return -EFAULT; break; @@ -1159,14 +1163,16 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, unlock_fb_info(info); break; case FBIOBLANK: - if (!lock_fb_info(info)) - return -ENODEV; console_lock(); + if (!lock_fb_info(info)) { + console_unlock(); + return -ENODEV; + } info->flags |= FBINFO_MISC_USEREVENT; ret = fb_blank(info, arg); info->flags &= ~FBINFO_MISC_USEREVENT; - console_unlock(); unlock_fb_info(info); + console_unlock(); break; default: if (!lock_fb_info(info)) -- 2.39.5