From d8e9b2b9097c117880dc22933239d05199c60b96 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 20 Feb 2017 14:58:25 +0100 Subject: [PATCH] drm/i915/gvt: Fix superfluous newline in GVT_DISPLAY_READY env var send_display_send_uevent() sends two environment variable, and the first one GVT_DISPLAY_READY is set including a new line at the end of the string; that is obviously superfluous and wrong -- at least, it *looks* so when you only read the code. However, it doesn't appear in the actual output by a (supposedly unexpected) trick. The code uses snprintf() and truncates the string in size 20 bytes. This makes the string as GVT_DISPLAY_READY=0 or ...=1 including the trailing NUL-letter. That is, the '\n' found in the format string is always cut off as a result. Although the code gives the correct result, it is confusing. This patch addresses it, just removing the superfluous '\n' from the format string for avoiding further confusion. If the argument "ready" were not a bool, the size 20 should be corrected as well. But it's a bool, so we can leave the magic number 20 as is for now. FWIW, the bug was spotted by a new GCC7 warning: drivers/gpu/drm/i915/gvt/handlers.c: In function 'pvinfo_mmio_write': drivers/gpu/drm/i915/gvt/handlers.c:1042:34: error: 'snprintf' output truncated before the last format character [-Werror=format-truncation=] snprintf(display_ready_str, 20, "GVT_DISPLAY_READY=%d\n", ready); ^~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/i915/gvt/handlers.c:1042:2: note: 'snprintf' output 21 bytes into a destination of size 20 snprintf(display_ready_str, 20, "GVT_DISPLAY_READY=%d\n", ready); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fixes: 04d348ae3f0a ("drm/i915/gvt: vGPU display virtualization") Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1025903 Reported-by: Richard Biener Cc: Signed-off-by: Takashi Iwai Signed-off-by: Zhenyu Wang --- drivers/gpu/drm/i915/gvt/handlers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c index e1abece853d4..a1880424ad32 100644 --- a/drivers/gpu/drm/i915/gvt/handlers.c +++ b/drivers/gpu/drm/i915/gvt/handlers.c @@ -1069,7 +1069,7 @@ static int send_display_ready_uevent(struct intel_vgpu *vgpu, int ready) char vmid_str[20]; char display_ready_str[20]; - snprintf(display_ready_str, 20, "GVT_DISPLAY_READY=%d\n", ready); + snprintf(display_ready_str, 20, "GVT_DISPLAY_READY=%d", ready); env[0] = display_ready_str; snprintf(vmid_str, 20, "VMID=%d", vgpu->id); -- 2.20.1