[PATCH] drm/gma500: fix double freeing
On Fri, Oct 2, 2015 at 5:56 PM, Sudip Mukherjee wrote: > On Thu, Oct 01, 2015 at 07:07:33PM +0200, Patrik Jakobsson wrote: >> On Wed, Sep 30, 2015 at 8:12 AM, Sudip Mukherjee >> wrote: >> > On Tue, Sep 29, 2015 at 03:20:35PM +0200, Patrik Jakobsson wrote: >> >> On Thu, Sep 24, 2015 at 5:57 PM, Sudip Mukherjee >> >> wrote: >> >> > On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: >> >> >> If backing->stolen is true then we were freeing backing by calling >> >> >> psb_gtt_free_range() but we called it again after unlocking the mutex. >> >> >> Lets make it NULL after freeing in psb_gtt_free_range() and check for >> >> >> NULL before calling the function for the second time. >> >> >> >> >> >> Signed-off-by: Sudip Mukherjee >> >> >> --- >> >> > Hi Patrik, >> >> > A gentle ping. >> >> > >> >> > regards >> >> > sudip >> >> >> >> Hi, sorry for the late reply. >> >> >> >> Why are we freeing the range twice in the first case? >> > I think, >> > if backing->stolen is true then backing is released using >> > psb_gtt_free_range() but if backing->stolen is false then the gem object >> > is freed but the backing is not yet freed. To free that backing >> > psb_gtt_free_range() has been called second time. My patch tried to fix >> > the possibility of backing->stolen being true and backing being freed 2 >> > times. >> > >> > regards >> > sudip >> >> There are some special handling of the stolen framebuffer that I don't >> remember entirely but the basic concept is that we free the backing >> when we drop the last reference on a gem object. That will trigger a >> psb_gtt_free_range(). So in this case it looks to me that the extra >> free is not needed at all. That's my quick reasoning, feel free to >> prove me wrong :) > > In this case we are allocating backing using psbfb_alloc() and so > backing->stolen is always true. So we can remove the backing->stolen > condition. And if drm_fb_helper_alloc_fbi() fails then we > are jumping to out_err1. So the fitst free will not be needed. Sounds good, could you also rename the labels to what they're doing now. I'm thinking out_release and out_unlock or something you feel is suitable. Thanks Patrik > diff --git a/drivers/gpu/drm/gma500/framebuffer.c > b/drivers/gpu/drm/gma500/framebuffer.c > index 2eaf1b3..932f07b 100644 > --- a/drivers/gpu/drm/gma500/framebuffer.c > +++ b/drivers/gpu/drm/gma500/framebuffer.c > @@ -466,11 +466,6 @@ static int psbfb_create(struct psb_fbdev *fbdev, > mutex_unlock(>struct_mutex); > return 0; > out_unref: > - if (backing->stolen) > - psb_gtt_free_range(dev, backing); > - else > - drm_gem_object_unreference(>gem); > - > drm_fb_helper_release_fbi(>psb_fb_helper); > out_err1: > mutex_unlock(>struct_mutex); > > > If it is ok, I can submit the v2. > > regards > sudip
[PATCH] drm/gma500: fix double freeing
On Thu, Oct 01, 2015 at 07:07:33PM +0200, Patrik Jakobsson wrote: > On Wed, Sep 30, 2015 at 8:12 AM, Sudip Mukherjee > wrote: > > On Tue, Sep 29, 2015 at 03:20:35PM +0200, Patrik Jakobsson wrote: > >> On Thu, Sep 24, 2015 at 5:57 PM, Sudip Mukherjee > >> wrote: > >> > On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: > >> >> If backing->stolen is true then we were freeing backing by calling > >> >> psb_gtt_free_range() but we called it again after unlocking the mutex. > >> >> Lets make it NULL after freeing in psb_gtt_free_range() and check for > >> >> NULL before calling the function for the second time. > >> >> > >> >> Signed-off-by: Sudip Mukherjee > >> >> --- > >> > Hi Patrik, > >> > A gentle ping. > >> > > >> > regards > >> > sudip > >> > >> Hi, sorry for the late reply. > >> > >> Why are we freeing the range twice in the first case? > > I think, > > if backing->stolen is true then backing is released using > > psb_gtt_free_range() but if backing->stolen is false then the gem object > > is freed but the backing is not yet freed. To free that backing > > psb_gtt_free_range() has been called second time. My patch tried to fix > > the possibility of backing->stolen being true and backing being freed 2 > > times. > > > > regards > > sudip > > There are some special handling of the stolen framebuffer that I don't > remember entirely but the basic concept is that we free the backing > when we drop the last reference on a gem object. That will trigger a > psb_gtt_free_range(). So in this case it looks to me that the extra > free is not needed at all. That's my quick reasoning, feel free to > prove me wrong :) In this case we are allocating backing using psbfb_alloc() and so backing->stolen is always true. So we can remove the backing->stolen condition. And if drm_fb_helper_alloc_fbi() fails then we are jumping to out_err1. So the fitst free will not be needed. diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c index 2eaf1b3..932f07b 100644 --- a/drivers/gpu/drm/gma500/framebuffer.c +++ b/drivers/gpu/drm/gma500/framebuffer.c @@ -466,11 +466,6 @@ static int psbfb_create(struct psb_fbdev *fbdev, mutex_unlock(>struct_mutex); return 0; out_unref: - if (backing->stolen) - psb_gtt_free_range(dev, backing); - else - drm_gem_object_unreference(>gem); - drm_fb_helper_release_fbi(>psb_fb_helper); out_err1: mutex_unlock(>struct_mutex); If it is ok, I can submit the v2. regards sudip
[PATCH] drm/gma500: fix double freeing
On Wed, Sep 30, 2015 at 8:12 AM, Sudip Mukherjee wrote: > On Tue, Sep 29, 2015 at 03:20:35PM +0200, Patrik Jakobsson wrote: >> On Thu, Sep 24, 2015 at 5:57 PM, Sudip Mukherjee >> wrote: >> > On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: >> >> If backing->stolen is true then we were freeing backing by calling >> >> psb_gtt_free_range() but we called it again after unlocking the mutex. >> >> Lets make it NULL after freeing in psb_gtt_free_range() and check for >> >> NULL before calling the function for the second time. >> >> >> >> Signed-off-by: Sudip Mukherjee >> >> --- >> > Hi Patrik, >> > A gentle ping. >> > >> > regards >> > sudip >> >> Hi, sorry for the late reply. >> >> Why are we freeing the range twice in the first case? > I think, > if backing->stolen is true then backing is released using > psb_gtt_free_range() but if backing->stolen is false then the gem object > is freed but the backing is not yet freed. To free that backing > psb_gtt_free_range() has been called second time. My patch tried to fix > the possibility of backing->stolen being true and backing being freed 2 > times. > > regards > sudip There are some special handling of the stolen framebuffer that I don't remember entirely but the basic concept is that we free the backing when we drop the last reference on a gem object. That will trigger a psb_gtt_free_range(). So in this case it looks to me that the extra free is not needed at all. That's my quick reasoning, feel free to prove me wrong :) Thanks Patrik
[PATCH] drm/gma500: fix double freeing
On Tue, Sep 29, 2015 at 03:20:35PM +0200, Patrik Jakobsson wrote: > On Thu, Sep 24, 2015 at 5:57 PM, Sudip Mukherjee > wrote: > > On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: > >> If backing->stolen is true then we were freeing backing by calling > >> psb_gtt_free_range() but we called it again after unlocking the mutex. > >> Lets make it NULL after freeing in psb_gtt_free_range() and check for > >> NULL before calling the function for the second time. > >> > >> Signed-off-by: Sudip Mukherjee > >> --- > > Hi Patrik, > > A gentle ping. > > > > regards > > sudip > > Hi, sorry for the late reply. > > Why are we freeing the range twice in the first case? I think, if backing->stolen is true then backing is released using psb_gtt_free_range() but if backing->stolen is false then the gem object is freed but the backing is not yet freed. To free that backing psb_gtt_free_range() has been called second time. My patch tried to fix the possibility of backing->stolen being true and backing being freed 2 times. regards sudip
[PATCH] drm/gma500: fix double freeing
On Thu, Sep 24, 2015 at 5:57 PM, Sudip Mukherjee wrote: > On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: >> If backing->stolen is true then we were freeing backing by calling >> psb_gtt_free_range() but we called it again after unlocking the mutex. >> Lets make it NULL after freeing in psb_gtt_free_range() and check for >> NULL before calling the function for the second time. >> >> Signed-off-by: Sudip Mukherjee >> --- > Hi Patrik, > A gentle ping. > > regards > sudip Hi, sorry for the late reply. Why are we freeing the range twice in the first case? -Patrik
[PATCH] drm/gma500: fix double freeing
On Wed, Sep 09, 2015 at 06:20:40PM +0530, Sudip Mukherjee wrote: > If backing->stolen is true then we were freeing backing by calling > psb_gtt_free_range() but we called it again after unlocking the mutex. > Lets make it NULL after freeing in psb_gtt_free_range() and check for > NULL before calling the function for the second time. > > Signed-off-by: Sudip Mukherjee > --- Hi Patrik, A gentle ping. regards sudip
[PATCH] drm/gma500: fix double freeing
If backing->stolen is true then we were freeing backing by calling psb_gtt_free_range() but we called it again after unlocking the mutex. Lets make it NULL after freeing in psb_gtt_free_range() and check for NULL before calling the function for the second time. Signed-off-by: Sudip Mukherjee --- drivers/gpu/drm/gma500/framebuffer.c | 3 ++- drivers/gpu/drm/gma500/gtt.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c index 2eaf1b3..381d7af 100644 --- a/drivers/gpu/drm/gma500/framebuffer.c +++ b/drivers/gpu/drm/gma500/framebuffer.c @@ -474,7 +474,8 @@ out_unref: drm_fb_helper_release_fbi(>psb_fb_helper); out_err1: mutex_unlock(>struct_mutex); - psb_gtt_free_range(dev, backing); + if (backing) + psb_gtt_free_range(dev, backing); return ret; } diff --git a/drivers/gpu/drm/gma500/gtt.c b/drivers/gpu/drm/gma500/gtt.c index ce015db..8130fa8 100644 --- a/drivers/gpu/drm/gma500/gtt.c +++ b/drivers/gpu/drm/gma500/gtt.c @@ -385,6 +385,7 @@ void psb_gtt_free_range(struct drm_device *dev, struct gtt_range *gt) WARN_ON(gt->in_gart && !gt->stolen); release_resource(>resource); kfree(gt); + gt = NULL; } static void psb_gtt_alloc(struct drm_device *dev) -- 1.9.1
