From ce540a24d53e1751a5b69224d5a7f5a59f2de7ad Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@gmail.com>
Date: Tue, 23 Sep 2014 13:33:53 +0200
Subject: [PATCH] Silence some "unchecked return-value" warnings

This adds some log-messages to ioctl() calls where we don't really care
for the return value. It isn't strictly necessary to look for those, but
lets be sure and print warnings. This silences gcc and coverity, and also
makes sure we get reports in case something goes wrong and we didn't
expect it to fail that way.
---
 src/libsystemd-terminal/grdev-drm.c | 23 ++++++++++++++++++-----
 src/login/logind-session.c          |  6 +++++-
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/libsystemd-terminal/grdev-drm.c b/src/libsystemd-terminal/grdev-drm.c
index 2e55ad326b..5c65c096de 100644
--- a/src/libsystemd-terminal/grdev-drm.c
+++ b/src/libsystemd-terminal/grdev-drm.c
@@ -1474,14 +1474,19 @@ static int grdrm_fb_new(grdrm_fb **out, grdrm_card *card, const struct drm_mode_
 
 grdrm_fb *grdrm_fb_free(grdrm_fb *fb) {
         unsigned int i;
+        int r;
 
         if (!fb)
                 return NULL;
 
         assert(fb->card);
 
-        if (fb->id > 0 && fb->card->fd >= 0)
-                ioctl(fb->card->fd, DRM_IOCTL_MODE_RMFB, fb->id);
+        if (fb->id > 0 && fb->card->fd >= 0) {
+                r = ioctl(fb->card->fd, DRM_IOCTL_MODE_RMFB, fb->id);
+                if (r < 0)
+                        log_debug("grdrm: %s: cannot delete framebuffer %" PRIu32 ": %m",
+                                  fb->card->base.name, fb->id);
+        }
 
         for (i = 0; i < ELEMENTSOF(fb->handles); ++i) {
                 struct drm_mode_destroy_dumb destroy_dumb = { };
@@ -1491,7 +1496,10 @@ grdrm_fb *grdrm_fb_free(grdrm_fb *fb) {
 
                 if (fb->handles[i] > 0 && fb->card->fd >= 0) {
                         destroy_dumb.handle = fb->handles[i];
-                        ioctl(fb->card->fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy_dumb);
+                        r = ioctl(fb->card->fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy_dumb);
+                        if (r < 0)
+                                log_debug("grdrm: %s: cannot destroy dumb-buffer %" PRIu32 ": %m",
+                                          fb->card->base.name, fb->handles[i]);
                 }
         }
 
@@ -2549,8 +2557,13 @@ static int unmanaged_card_new(grdev_card **out, grdev_session *session, struct u
                           basecard->session->name, basecard->name, cu->devnode);
         } else {
                 /* We might get DRM-Master implicitly on open(); drop it immediately
-                 * so we acquire it only once we're actually enabled. */
-                ioctl(fd, DRM_IOCTL_DROP_MASTER, 0);
+                 * so we acquire it only once we're actually enabled. We don't
+                 * really care whether this call fails or not, but lets log any
+                 * weird errors, anyway. */
+                r = ioctl(fd, DRM_IOCTL_DROP_MASTER, 0);
+                if (r < 0 && errno != EACCES && errno != EINVAL)
+                        log_debug("grdrm: %s/%s: cannot drop DRM-Master: %m",
+                                  basecard->session->name, basecard->name);
 
                 r = grdrm_card_open(&cu->card, fd);
                 if (r < 0)
diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index 477ac9ab1b..65bbb77750 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -1054,6 +1054,8 @@ void session_restore_vt(Session *s) {
 }
 
 void session_leave_vt(Session *s) {
+        int r;
+
         assert(s);
 
         /* This is called whenever we get a VT-switch signal from the kernel.
@@ -1071,7 +1073,9 @@ void session_leave_vt(Session *s) {
                 return;
 
         session_device_pause_all(s);
-        ioctl(s->vtfd, VT_RELDISP, 1);
+        r = ioctl(s->vtfd, VT_RELDISP, 1);
+        if (r < 0)
+                log_debug("Cannot release VT of session %s: %m", s->id);
 }
 
 bool session_is_controller(Session *s, const char *sender) {