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Commit a63187ac authored by Adrian Salido-Moreno's avatar Adrian Salido-Moreno
Browse files

msm: mdss: avoid race conditions during fb release 



During fb release we should release all resources that are associated to
that process. However, in current release function this can lead to
kickoff being done, if this is done while display thread is running
there can be race condition between the updates from two different
threads. Fix this by pushing the commit through the display thread in
cases where display thread should be running, or otherwise shutdown this
thread and do it along with panel blanking.

Change-Id: I9ff6316c18adfdb67d0250a144ddc2f9f2634273
Signed-off-by: default avatarAdrian Salido-Moreno <adrianm@codeaurora.org>
parent 5f0fb8f9

drivers/video/msm/mdss/mdss_fb.c

+16 −26
Original line number Diff line number Diff line
@@ -2111,7 +2111,7 @@ static int mdss_fb_release_all(struct fb_info *info, bool release_all) 
		unknown_pid = false;



		pr_debug("found process %s pid=%d mfd->ref=%d pinfo->ref=%d\n",

			task->comm, mfd->ref_cnt, pinfo->pid, pinfo->ref_cnt);

			task->comm, pinfo->pid, mfd->ref_cnt, pinfo->ref_cnt);



		proc_info = mdss_fb_release_file_entry(info, pinfo,

								release_all);
@@ -2136,10 +2136,6 @@ static int mdss_fb_release_all(struct fb_info *info, bool release_all) 
			pm_runtime_put(info->dev);

		} while (release_all && pinfo->ref_cnt);



		/* we need to stop display thread before release */

		if (release_all && mfd->disp_thread)

			mdss_fb_stop_disp_thread(mfd);



		if (pinfo->ref_cnt == 0) {

			list_del(&pinfo->list);

			kfree(pinfo);
@@ -2170,27 +2166,10 @@ static int mdss_fb_release_all(struct fb_info *info, bool release_all) 
		}

	}



	if (release_needed) {

		pr_debug("current process=%s pid=%d known pid=%d mfd->ref=%d\n",

			task->comm, current->tgid, pid, mfd->ref_cnt);



		if (mfd->mdp.release_fnc) {

			ret = mfd->mdp.release_fnc(mfd, false, pid);

			if (ret)

				pr_err("error releasing fb%d for current pid=%d known pid=%d\n",

					mfd->index, current->tgid, pid);

		}

	} else if (release_all && mfd->ref_cnt) {

		pr_err("reference count mismatch with proc list entries\n");

	}



	if (!mfd->ref_cnt) {

		if (mfd->mdp.release_fnc) {

			ret = mfd->mdp.release_fnc(mfd, true, pid);

			if (ret)

				pr_err("error fb%d release current process=%s pid=%d known pid=%d\n",

				    mfd->index, task->comm, current->tgid, pid);

		}

	if (!mfd->ref_cnt || release_all) {

		/* resources (if any) will be released during blank */

		if (mfd->mdp.release_fnc)

			mfd->mdp.release_fnc(mfd, true, pid);



		if (mfd->fb_ion_handle)

			mdss_fb_free_fb_ion_memory(mfd);
@@ -2203,6 +2182,17 @@ static int mdss_fb_release_all(struct fb_info *info, bool release_all) 
			return ret;

		}

		atomic_set(&mfd->ioctl_ref_cnt, 0);

	} else if (release_needed) {

		pr_debug("current process=%s pid=%d known pid=%d mfd->ref=%d\n",

			task->comm, current->tgid, pid, mfd->ref_cnt);



		if (mfd->mdp.release_fnc) {

			ret = mfd->mdp.release_fnc(mfd, false, pid);



			/* display commit is needed to release resources */

			if (ret)

				mdss_fb_pan_display(&mfd->fbi->var, mfd->fbi);

		}

	}



	return ret;

drivers/video/msm/mdss/mdss_mdp_overlay.c

+3 −4
Original line number Diff line number Diff line
@@ -1683,6 +1683,8 @@ done: 
 *

 * Release any resources allocated by calling process, this can be called

 * on fb_release to release any overlays/rotator sessions left open.

 *

 * Return number of resources released

 */

static int __mdss_mdp_overlay_release_all(struct msm_fb_data_type *mfd,

	bool release_all, uint32_t pid)
@@ -1721,9 +1723,6 @@ static int __mdss_mdp_overlay_release_all(struct msm_fb_data_type *mfd, 
	}

	mutex_unlock(&mdp5_data->ov_lock);



	if (cnt)

		mfd->mdp.kickoff_fnc(mfd, NULL);



	list_for_each_entry_safe(rot, tmp, &mdp5_data->rot_proc_list, list) {

		if (rot->pid == pid) {

			if (!list_empty(&rot->list))
@@ -1732,7 +1731,7 @@ static int __mdss_mdp_overlay_release_all(struct msm_fb_data_type *mfd, 
		}

	}



	return 0;

	return cnt;

}



static int mdss_mdp_overlay_play_wait(struct msm_fb_data_type *mfd,