From: Niranjan Vishwanathapura <niranjana.vishwanathapura@intel.com> To: Chris Wilson <chris@chris-wilson.co.uk> Cc: intel-gfx@lists.freedesktop.org Subject: Re: [PATCH 3/3] drm/i915: Use rcu_dereference for rcu protected pointer Date: Wed, 6 Nov 2019 21:05:26 -0800 [thread overview] Message-ID: <20191107050525.GG19940@nvishwa1-DESK.sc.intel.com> (raw) In-Reply-To: <157303037798.18566.12503418453281213801@skylake-alporthouse-com> On Wed, Nov 06, 2019 at 08:52:58AM +0000, Chris Wilson wrote: >Quoting Niranjan Vishwanathapura (2019-11-06 02:16:42) >> On Wed, Nov 06, 2019 at 12:36:47AM +0000, Chris Wilson wrote: >> >Quoting Niranjana Vishwanathapura (2019-11-06 00:02:05) >> >> 'ctx\->vm' is rcu protected, so use rcu_dereference inside >> >> read side critical section. It fixes a sparse warning. >> >> >> >> Cc: Chris P Wilson <chris.p.wilson@intel.com> >> >> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com> >> >> --- >> >> drivers/gpu/drm/i915/gem/i915_gem_context.c | 9 +++++---- >> >> 1 file changed, 5 insertions(+), 4 deletions(-) >> >> >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> index de6e55af82cf..d3a622f60fd9 100644 >> >> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> @@ -1002,12 +1002,13 @@ static int get_ppgtt(struct drm_i915_file_private *file_priv, >> >> struct i915_address_space *vm; >> >> int ret; >> >> >> >> - if (!rcu_access_pointer(ctx->vm)) >> >> - return -ENODEV; >> > >> >This is correctly serialised by the caller. >> >> Ok, is this worth fixing the sparse warning? > > CHECK drivers/gpu/drm/i915/gem/i915_gem_context.c >drivers/gpu/drm/i915/gem/i915_gem_context.c:2087:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2088:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2089:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2090:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2091:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2092:17: error: bad integer constant expression > >Odd. I am seeing, CHECK drivers/gpu/drm/i915/gem/i915_gem_context.c drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: warning: incorrect type in argument 1 (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: expected struct i915_address_space *vm drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: got struct i915_address_space [noderef] <asn:4> *vm drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: warning: incorrect type in argument 1 (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: expected struct i915_gem_engines *e drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: got struct i915_gem_engines [noderef] <asn:4> *engines drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: warning: incorrect type in assignment (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: expected struct i915_gem_engines *clone drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: got struct i915_gem_engines [noderef] <asn:4> *engines > >Sure, for correctness see clone_vm(). Ok, I can put a common helper function like vm_get_rcu_safe(ctx). Niranjana >-Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
WARNING: multiple messages have this Message-ID (diff)
From: Niranjan Vishwanathapura <niranjana.vishwanathapura@intel.com> To: Chris Wilson <chris@chris-wilson.co.uk> Cc: intel-gfx@lists.freedesktop.org Subject: Re: [Intel-gfx] [PATCH 3/3] drm/i915: Use rcu_dereference for rcu protected pointer Date: Wed, 6 Nov 2019 21:05:26 -0800 [thread overview] Message-ID: <20191107050525.GG19940@nvishwa1-DESK.sc.intel.com> (raw) Message-ID: <20191107050526.XB1yR5fo-l-h0_Ggw5_g-Qd96fSIRJTgqRfdLXoh9Zo@z> (raw) In-Reply-To: <157303037798.18566.12503418453281213801@skylake-alporthouse-com> On Wed, Nov 06, 2019 at 08:52:58AM +0000, Chris Wilson wrote: >Quoting Niranjan Vishwanathapura (2019-11-06 02:16:42) >> On Wed, Nov 06, 2019 at 12:36:47AM +0000, Chris Wilson wrote: >> >Quoting Niranjana Vishwanathapura (2019-11-06 00:02:05) >> >> 'ctx\->vm' is rcu protected, so use rcu_dereference inside >> >> read side critical section. It fixes a sparse warning. >> >> >> >> Cc: Chris P Wilson <chris.p.wilson@intel.com> >> >> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com> >> >> --- >> >> drivers/gpu/drm/i915/gem/i915_gem_context.c | 9 +++++---- >> >> 1 file changed, 5 insertions(+), 4 deletions(-) >> >> >> >> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> index de6e55af82cf..d3a622f60fd9 100644 >> >> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c >> >> @@ -1002,12 +1002,13 @@ static int get_ppgtt(struct drm_i915_file_private *file_priv, >> >> struct i915_address_space *vm; >> >> int ret; >> >> >> >> - if (!rcu_access_pointer(ctx->vm)) >> >> - return -ENODEV; >> > >> >This is correctly serialised by the caller. >> >> Ok, is this worth fixing the sparse warning? > > CHECK drivers/gpu/drm/i915/gem/i915_gem_context.c >drivers/gpu/drm/i915/gem/i915_gem_context.c:2087:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2088:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2089:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2090:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2091:17: error: bad integer constant expression >drivers/gpu/drm/i915/gem/i915_gem_context.c:2092:17: error: bad integer constant expression > >Odd. I am seeing, CHECK drivers/gpu/drm/i915/gem/i915_gem_context.c drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: warning: incorrect type in argument 1 (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: expected struct i915_address_space *vm drivers/gpu/drm/i915/gem/i915_gem_context.c:1009:29: got struct i915_address_space [noderef] <asn:4> *vm drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: warning: incorrect type in argument 1 (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: expected struct i915_gem_engines *e drivers/gpu/drm/i915/gem/i915_gem_context.c:1958:25: got struct i915_gem_engines [noderef] <asn:4> *engines drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: warning: incorrect type in assignment (different address spaces) drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: expected struct i915_gem_engines *clone drivers/gpu/drm/i915/gem/i915_gem_context.c:1993:15: got struct i915_gem_engines [noderef] <asn:4> *engines > >Sure, for correctness see clone_vm(). Ok, I can put a common helper function like vm_get_rcu_safe(ctx). Niranjana >-Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2019-11-07 5:17 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20191106000205.22480-1-niranjana.vishwanathapura@intel.com> [not found] ` <20191106000205.22480-4-niranjana.vishwanathapura@intel.com> 2019-11-06 0:36 ` [PATCH 3/3] drm/i915: Use rcu_dereference for rcu protected pointer Chris Wilson 2019-11-06 0:36 ` [Intel-gfx] " Chris Wilson 2019-11-06 2:16 ` Niranjan Vishwanathapura 2019-11-06 2:16 ` [Intel-gfx] " Niranjan Vishwanathapura 2019-11-06 8:52 ` Chris Wilson 2019-11-06 8:52 ` [Intel-gfx] " Chris Wilson 2019-11-07 5:05 ` Niranjan Vishwanathapura [this message] 2019-11-07 5:05 ` Niranjan Vishwanathapura 2019-11-07 9:49 ` Chris Wilson 2019-11-07 9:49 ` [Intel-gfx] " Chris Wilson [not found] ` <20191106000205.22480-3-niranjana.vishwanathapura@intel.com> 2019-11-06 0:37 ` [PATCH 2/3] drm/i915: Check for ips_mchdev being NULL Chris Wilson 2019-11-06 0:37 ` [Intel-gfx] " Chris Wilson 2019-11-06 2:14 ` Niranjan Vishwanathapura 2019-11-06 2:14 ` [Intel-gfx] " Niranjan Vishwanathapura 2019-11-06 8:40 ` Chris Wilson 2019-11-06 8:40 ` [Intel-gfx] " Chris Wilson [not found] ` <20191106000205.22480-2-niranjana.vishwanathapura@intel.com> 2019-11-06 0:42 ` [PATCH 1/3] drm/i915: Remove unwanted rcu_read_lock/unlock Chris Wilson 2019-11-06 0:42 ` [Intel-gfx] " Chris Wilson
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