[PATCH] staging: android: Remove set but unused variable in ashmem.c

[PATCH] staging: android: Remove set but unused variable in ashmem.c

[Fabio M. De Francesco]

Remove variable 'inode' tnat is set but unused. Issue detected
by building with warning option -Wunused-but-set-variable.

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 drivers/staging/android/ashmem.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index ddbde3f8430e..606e988d3f63 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -406,7 +406,6 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 	if (!asma->file) {
 		char *name = ASHMEM_NAME_DEF;
 		struct file *vmfile;
-		struct inode *inode;
 
 		if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
 			name = asma->name;
@@ -418,7 +417,6 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 			goto out;
 		}
 		vmfile->f_mode |= FMODE_LSEEK;
-		inode = file_inode(vmfile);
 		lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
 		asma->file = vmfile;
 		/*
-- 
2.32.0

Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[Suren Baghdasaryan]

On Fri, Jul 23, 2021 at 1:05 PM Fabio M. De Francesco
<fmdefrancesco@gmail.com> wrote:
>
> Remove variable 'inode' tnat is set but unused. Issue detected
> by building with warning option -Wunused-but-set-variable.
>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---
>  drivers/staging/android/ashmem.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
> index ddbde3f8430e..606e988d3f63 100644
> --- a/drivers/staging/android/ashmem.c
> +++ b/drivers/staging/android/ashmem.c
> @@ -406,7 +406,6 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
>         if (!asma->file) {
>                 char *name = ASHMEM_NAME_DEF;
>                 struct file *vmfile;
> -               struct inode *inode;
>
>                 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
>                         name = asma->name;
> @@ -418,7 +417,6 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
>                         goto out;
>                 }
>                 vmfile->f_mode |= FMODE_LSEEK;
> -               inode = file_inode(vmfile);
>                 lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);

How about its usage in the above lockdep_set_class(&inode->i_rwsem,
...) call? I'm guessing you are building with CONFIG_LOCKDEP=n.
Have you tried adding __maybe_unused in inode variable definition to
get rid of the warning?


>                 asma->file = vmfile;
>                 /*
> --
> 2.32.0
>

Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 9113 bytes --]

Hi "Fabio,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on staging/staging-testing]

url:    https://github.com/0day-ci/linux/commits/Fabio-M-De-Francesco/staging-android-Remove-set-but-unused-variable-in-ashmem-c/20210724-040651
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git f133717efc6f28052667daf682e99ffd4b3d7588
config: arm64-randconfig-r015-20210723 (attached as .config)
compiler: aarch64-linux-gcc (GCC) 10.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/7e8f2aa391f91bb404e9c1b508cf3d13b0cfde94
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Fabio-M-De-Francesco/staging-android-Remove-set-but-unused-variable-in-ashmem-c/20210724-040651
        git checkout 7e8f2aa391f91bb404e9c1b508cf3d13b0cfde94
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/staging/android/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from include/linux/spinlock.h:59,
                    from include/linux/wait.h:9,
                    from include/linux/wait_bit.h:8,
                    from include/linux/fs.h:6,
                    from drivers/staging/android/ashmem.c:16:
   drivers/staging/android/ashmem.c: In function 'ashmem_mmap':
>> drivers/staging/android/ashmem.c:420:22: error: 'inode' undeclared (first use in this function)
     420 |   lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
         |                      ^~~~~
   include/linux/lockdep.h:218:27: note: in definition of macro 'lockdep_set_class'
     218 |  lockdep_init_map_waits(&(lock)->dep_map, #key, key, 0, \
         |                           ^~~~
   drivers/staging/android/ashmem.c:420:22: note: each undeclared identifier is reported only once for each function it appears in
     420 |   lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
         |                      ^~~~~
   include/linux/lockdep.h:218:27: note: in definition of macro 'lockdep_set_class'
     218 |  lockdep_init_map_waits(&(lock)->dep_map, #key, key, 0, \
         |                           ^~~~


vim +/inode +420 drivers/staging/android/ashmem.c

6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  377  
11980c2ac4ccfa Robert Love        2011-12-20  378  static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
11980c2ac4ccfa Robert Love        2011-12-20  379  {
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  380  	static struct file_operations vmfile_fops;
11980c2ac4ccfa Robert Love        2011-12-20  381  	struct ashmem_area *asma = file->private_data;
11980c2ac4ccfa Robert Love        2011-12-20  382  	int ret = 0;
11980c2ac4ccfa Robert Love        2011-12-20  383  
11980c2ac4ccfa Robert Love        2011-12-20  384  	mutex_lock(&ashmem_mutex);
11980c2ac4ccfa Robert Love        2011-12-20  385  
11980c2ac4ccfa Robert Love        2011-12-20  386  	/* user needs to SET_SIZE before mapping */
59848d6aded59a Alistair Strachan  2018-06-19  387  	if (!asma->size) {
11980c2ac4ccfa Robert Love        2011-12-20  388  		ret = -EINVAL;
11980c2ac4ccfa Robert Love        2011-12-20  389  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  390  	}
11980c2ac4ccfa Robert Love        2011-12-20  391  
8632c614565d0c Alistair Strachan  2018-06-19  392  	/* requested mapping size larger than object size */
8632c614565d0c Alistair Strachan  2018-06-19  393  	if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
11980c2ac4ccfa Robert Love        2011-12-20  394  		ret = -EINVAL;
11980c2ac4ccfa Robert Love        2011-12-20  395  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  396  	}
11980c2ac4ccfa Robert Love        2011-12-20  397  
11980c2ac4ccfa Robert Love        2011-12-20  398  	/* requested protection bits must match our allowed protection mask */
59848d6aded59a Alistair Strachan  2018-06-19  399  	if ((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
59848d6aded59a Alistair Strachan  2018-06-19  400  	    calc_vm_prot_bits(PROT_MASK, 0)) {
11980c2ac4ccfa Robert Love        2011-12-20  401  		ret = -EPERM;
11980c2ac4ccfa Robert Love        2011-12-20  402  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  403  	}
56f76fc68492af Arve Hjønnevåg     2011-12-20  404  	vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
11980c2ac4ccfa Robert Love        2011-12-20  405  
11980c2ac4ccfa Robert Love        2011-12-20  406  	if (!asma->file) {
11980c2ac4ccfa Robert Love        2011-12-20  407  		char *name = ASHMEM_NAME_DEF;
11980c2ac4ccfa Robert Love        2011-12-20  408  		struct file *vmfile;
11980c2ac4ccfa Robert Love        2011-12-20  409  
11980c2ac4ccfa Robert Love        2011-12-20  410  		if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
11980c2ac4ccfa Robert Love        2011-12-20  411  			name = asma->name;
11980c2ac4ccfa Robert Love        2011-12-20  412  
11980c2ac4ccfa Robert Love        2011-12-20  413  		/* ... and allocate the backing shmem file */
11980c2ac4ccfa Robert Love        2011-12-20  414  		vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
7f44cb0ba88b40 Viresh Kumar       2015-07-31  415  		if (IS_ERR(vmfile)) {
11980c2ac4ccfa Robert Love        2011-12-20  416  			ret = PTR_ERR(vmfile);
11980c2ac4ccfa Robert Love        2011-12-20  417  			goto out;
11980c2ac4ccfa Robert Love        2011-12-20  418  		}
97fbfef6bd5978 Shuxiao Zhang      2017-04-06  419  		vmfile->f_mode |= FMODE_LSEEK;
3e338d3c95c735 Suren Baghdasaryan 2020-07-30 @420  		lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
11980c2ac4ccfa Robert Love        2011-12-20  421  		asma->file = vmfile;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  422  		/*
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  423  		 * override mmap operation of the vmfile so that it can't be
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  424  		 * remapped which would lead to creation of a new vma with no
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  425  		 * asma permission checks. Have to override get_unmapped_area
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  426  		 * as well to prevent VM_BUG_ON check for f_ops modification.
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  427  		 */
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  428  		if (!vmfile_fops.mmap) {
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  429  			vmfile_fops = *vmfile->f_op;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  430  			vmfile_fops.mmap = ashmem_vmfile_mmap;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  431  			vmfile_fops.get_unmapped_area =
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  432  					ashmem_vmfile_get_unmapped_area;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  433  		}
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  434  		vmfile->f_op = &vmfile_fops;
11980c2ac4ccfa Robert Love        2011-12-20  435  	}
11980c2ac4ccfa Robert Love        2011-12-20  436  	get_file(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  437  
11980c2ac4ccfa Robert Love        2011-12-20  438  	/*
11980c2ac4ccfa Robert Love        2011-12-20  439  	 * XXX - Reworked to use shmem_zero_setup() instead of
11980c2ac4ccfa Robert Love        2011-12-20  440  	 * shmem_set_file while we're in staging. -jstultz
11980c2ac4ccfa Robert Love        2011-12-20  441  	 */
11980c2ac4ccfa Robert Love        2011-12-20  442  	if (vma->vm_flags & VM_SHARED) {
11980c2ac4ccfa Robert Love        2011-12-20  443  		ret = shmem_zero_setup(vma);
11980c2ac4ccfa Robert Love        2011-12-20  444  		if (ret) {
11980c2ac4ccfa Robert Love        2011-12-20  445  			fput(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  446  			goto out;
11980c2ac4ccfa Robert Love        2011-12-20  447  		}
44960f2a7b63e2 John Stultz        2018-07-31  448  	} else {
44960f2a7b63e2 John Stultz        2018-07-31  449  		vma_set_anonymous(vma);
11980c2ac4ccfa Robert Love        2011-12-20  450  	}
11980c2ac4ccfa Robert Love        2011-12-20  451  
295992fb815e79 Christian König    2020-09-14  452  	vma_set_file(vma, asma->file);
295992fb815e79 Christian König    2020-09-14  453  	/* XXX: merge this with the get_file() above if possible */
295992fb815e79 Christian König    2020-09-14  454  	fput(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  455  
11980c2ac4ccfa Robert Love        2011-12-20  456  out:
11980c2ac4ccfa Robert Love        2011-12-20  457  	mutex_unlock(&ashmem_mutex);
11980c2ac4ccfa Robert Love        2011-12-20  458  	return ret;
11980c2ac4ccfa Robert Love        2011-12-20  459  }
11980c2ac4ccfa Robert Love        2011-12-20  460  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 33436 bytes --]

Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 8500 bytes --]

Hi "Fabio,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on staging/staging-testing]

url:    https://github.com/0day-ci/linux/commits/Fabio-M-De-Francesco/staging-android-Remove-set-but-unused-variable-in-ashmem-c/20210724-040651
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git f133717efc6f28052667daf682e99ffd4b3d7588
config: x86_64-randconfig-a002-20210723 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9625ca5b602616b2f5584e8a49ba93c52c141e40)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/7e8f2aa391f91bb404e9c1b508cf3d13b0cfde94
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Fabio-M-De-Francesco/staging-android-Remove-set-but-unused-variable-in-ashmem-c/20210724-040651
        git checkout 7e8f2aa391f91bb404e9c1b508cf3d13b0cfde94
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> drivers/staging/android/ashmem.c:420:22: error: use of undeclared identifier 'inode'
                   lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
                                      ^
>> drivers/staging/android/ashmem.c:420:22: error: use of undeclared identifier 'inode'
>> drivers/staging/android/ashmem.c:420:22: error: use of undeclared identifier 'inode'
   3 errors generated.


vim +/inode +420 drivers/staging/android/ashmem.c

6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  377  
11980c2ac4ccfa Robert Love        2011-12-20  378  static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
11980c2ac4ccfa Robert Love        2011-12-20  379  {
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  380  	static struct file_operations vmfile_fops;
11980c2ac4ccfa Robert Love        2011-12-20  381  	struct ashmem_area *asma = file->private_data;
11980c2ac4ccfa Robert Love        2011-12-20  382  	int ret = 0;
11980c2ac4ccfa Robert Love        2011-12-20  383  
11980c2ac4ccfa Robert Love        2011-12-20  384  	mutex_lock(&ashmem_mutex);
11980c2ac4ccfa Robert Love        2011-12-20  385  
11980c2ac4ccfa Robert Love        2011-12-20  386  	/* user needs to SET_SIZE before mapping */
59848d6aded59a Alistair Strachan  2018-06-19  387  	if (!asma->size) {
11980c2ac4ccfa Robert Love        2011-12-20  388  		ret = -EINVAL;
11980c2ac4ccfa Robert Love        2011-12-20  389  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  390  	}
11980c2ac4ccfa Robert Love        2011-12-20  391  
8632c614565d0c Alistair Strachan  2018-06-19  392  	/* requested mapping size larger than object size */
8632c614565d0c Alistair Strachan  2018-06-19  393  	if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
11980c2ac4ccfa Robert Love        2011-12-20  394  		ret = -EINVAL;
11980c2ac4ccfa Robert Love        2011-12-20  395  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  396  	}
11980c2ac4ccfa Robert Love        2011-12-20  397  
11980c2ac4ccfa Robert Love        2011-12-20  398  	/* requested protection bits must match our allowed protection mask */
59848d6aded59a Alistair Strachan  2018-06-19  399  	if ((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
59848d6aded59a Alistair Strachan  2018-06-19  400  	    calc_vm_prot_bits(PROT_MASK, 0)) {
11980c2ac4ccfa Robert Love        2011-12-20  401  		ret = -EPERM;
11980c2ac4ccfa Robert Love        2011-12-20  402  		goto out;
11980c2ac4ccfa Robert Love        2011-12-20  403  	}
56f76fc68492af Arve Hjønnevåg     2011-12-20  404  	vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
11980c2ac4ccfa Robert Love        2011-12-20  405  
11980c2ac4ccfa Robert Love        2011-12-20  406  	if (!asma->file) {
11980c2ac4ccfa Robert Love        2011-12-20  407  		char *name = ASHMEM_NAME_DEF;
11980c2ac4ccfa Robert Love        2011-12-20  408  		struct file *vmfile;
11980c2ac4ccfa Robert Love        2011-12-20  409  
11980c2ac4ccfa Robert Love        2011-12-20  410  		if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
11980c2ac4ccfa Robert Love        2011-12-20  411  			name = asma->name;
11980c2ac4ccfa Robert Love        2011-12-20  412  
11980c2ac4ccfa Robert Love        2011-12-20  413  		/* ... and allocate the backing shmem file */
11980c2ac4ccfa Robert Love        2011-12-20  414  		vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
7f44cb0ba88b40 Viresh Kumar       2015-07-31  415  		if (IS_ERR(vmfile)) {
11980c2ac4ccfa Robert Love        2011-12-20  416  			ret = PTR_ERR(vmfile);
11980c2ac4ccfa Robert Love        2011-12-20  417  			goto out;
11980c2ac4ccfa Robert Love        2011-12-20  418  		}
97fbfef6bd5978 Shuxiao Zhang      2017-04-06  419  		vmfile->f_mode |= FMODE_LSEEK;
3e338d3c95c735 Suren Baghdasaryan 2020-07-30 @420  		lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
11980c2ac4ccfa Robert Love        2011-12-20  421  		asma->file = vmfile;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  422  		/*
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  423  		 * override mmap operation of the vmfile so that it can't be
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  424  		 * remapped which would lead to creation of a new vma with no
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  425  		 * asma permission checks. Have to override get_unmapped_area
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  426  		 * as well to prevent VM_BUG_ON check for f_ops modification.
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  427  		 */
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  428  		if (!vmfile_fops.mmap) {
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  429  			vmfile_fops = *vmfile->f_op;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  430  			vmfile_fops.mmap = ashmem_vmfile_mmap;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  431  			vmfile_fops.get_unmapped_area =
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  432  					ashmem_vmfile_get_unmapped_area;
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  433  		}
6d67b0290b4b84 Suren Baghdasaryan 2020-01-27  434  		vmfile->f_op = &vmfile_fops;
11980c2ac4ccfa Robert Love        2011-12-20  435  	}
11980c2ac4ccfa Robert Love        2011-12-20  436  	get_file(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  437  
11980c2ac4ccfa Robert Love        2011-12-20  438  	/*
11980c2ac4ccfa Robert Love        2011-12-20  439  	 * XXX - Reworked to use shmem_zero_setup() instead of
11980c2ac4ccfa Robert Love        2011-12-20  440  	 * shmem_set_file while we're in staging. -jstultz
11980c2ac4ccfa Robert Love        2011-12-20  441  	 */
11980c2ac4ccfa Robert Love        2011-12-20  442  	if (vma->vm_flags & VM_SHARED) {
11980c2ac4ccfa Robert Love        2011-12-20  443  		ret = shmem_zero_setup(vma);
11980c2ac4ccfa Robert Love        2011-12-20  444  		if (ret) {
11980c2ac4ccfa Robert Love        2011-12-20  445  			fput(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  446  			goto out;
11980c2ac4ccfa Robert Love        2011-12-20  447  		}
44960f2a7b63e2 John Stultz        2018-07-31  448  	} else {
44960f2a7b63e2 John Stultz        2018-07-31  449  		vma_set_anonymous(vma);
11980c2ac4ccfa Robert Love        2011-12-20  450  	}
11980c2ac4ccfa Robert Love        2011-12-20  451  
295992fb815e79 Christian König    2020-09-14  452  	vma_set_file(vma, asma->file);
295992fb815e79 Christian König    2020-09-14  453  	/* XXX: merge this with the get_file() above if possible */
295992fb815e79 Christian König    2020-09-14  454  	fput(asma->file);
11980c2ac4ccfa Robert Love        2011-12-20  455  
11980c2ac4ccfa Robert Love        2011-12-20  456  out:
11980c2ac4ccfa Robert Love        2011-12-20  457  	mutex_unlock(&ashmem_mutex);
11980c2ac4ccfa Robert Love        2011-12-20  458  	return ret;
11980c2ac4ccfa Robert Love        2011-12-20  459  }
11980c2ac4ccfa Robert Love        2011-12-20  460  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[Fabio M. De Francesco]

On Friday, July 23, 2021 10:14:46 PM CEST Suren Baghdasaryan wrote:
> On Fri, Jul 23, 2021 at 1:05 PM Fabio M. De Francesco
> 
> <fmdefrancesco@gmail.com> wrote:
> > Remove variable 'inode' tnat is set but unused. Issue detected
> > by building with warning option -Wunused-but-set-variable.
> > 
> > [...]
> > 
> > -               inode = file_inode(vmfile);
> > 
> >                 lockdep_set_class(&inode->i_rwsem, 
&backing_shmem_inode_class);
> 
> How about its usage in the above lockdep_set_class(&inode->i_rwsem,
> ...) call? 

I'm sorry. I didn't notice that 'inode' is used soon after assignment, just in 
the line that follows it. I was also too confident that rebuilding the driver 
would have triggered an error if it is used somewhere else. I was obviously 
wrong.

Furthermore, I usually automatically search with grep or other tools for other 
occurrences of a symbol in the function and the file, but this time I must 
have forgotten to do that.

> I'm guessing you are building with CONFIG_LOCKDEP=n.

Actually my .config sets CONFIG_LOCKDEP_SUPPORT=y. Did you refer to this? 
There is no CONFIG_LOCKDEP in the file.
 
I've just run "make clean && make C=2 -j8 drivers/staging/android/ W=1" one 
more time and it still builds.  How is it possible that the code builds 
correctly with my configuration? 

This is the output (the last two lines) of 'make':

CC      drivers/staging/android/ashmem.o
AR      drivers/staging/android/built-in.

There are no errors or warnings, even with that "lockdep_set_class(&inode-
>i_rwsem, &backing_shmem_inode_class);" left as-is after 'inode' removal. 

I really can't understand what I'm missing.

> Have you tried adding __maybe_unused in inode variable definition to
> get rid of the warning?
> 
Actually, I didn't know that directive that you mention. I'll read the 
documentation and, if and where suited, I'll use it.

Thanks,

Fabio
>
> > [...]
> > --
> > 2.32.0

Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[Dan Carpenter]

On Sat, Jul 24, 2021 at 09:49:35AM +0200, Fabio M. De Francesco wrote:
> On Friday, July 23, 2021 10:14:46 PM CEST Suren Baghdasaryan wrote:
> > How about its usage in the above lockdep_set_class(&inode->i_rwsem,
> > ...) call? 
> 
> I'm sorry. I didn't notice that 'inode' is used soon after assignment, just in 
> the line that follows it. I was also too confident that rebuilding the driver 
> would have triggered an error if it is used somewhere else. I was obviously 
> wrong.
> 
> Furthermore, I usually automatically search with grep or other tools for other 
> occurrences of a symbol in the function and the file, but this time I must 
> have forgotten to do that.

Another trick which would have helped is to try find out which patch
forgot to remove the "inode" variale, because that developer would have
seen the warning as well.


> 
> > I'm guessing you are building with CONFIG_LOCKDEP=n.
> 
> Actually my .config sets CONFIG_LOCKDEP_SUPPORT=y. Did you refer to this? 
> There is no CONFIG_LOCKDEP in the file.

Use make nconfig and then use f8 to search for CONFIG_LOCKDEP.

regards,
dan carpenter

Re: [PATCH] staging: android: Remove set but unused variable in ashmem.c

[Fabio M. De Francesco]

Hello Dan,

On Monday, July 26, 2021 3:44:54 PM CEST Dan Carpenter wrote:
> On Sat, Jul 24, 2021 at 09:49:35AM +0200, Fabio M. De Francesco wrote:
> >
> > [...]
> >
> Another trick which would have helped is to try find out which patch
> forgot to remove the "inode" variable, because that developer would have
> seen the warning as well.
> 
> > > I'm guessing you are building with CONFIG_LOCKDEP=n.
> > 
> > Actually my .config sets CONFIG_LOCKDEP_SUPPORT=y. Did you refer to this?
> > There is no CONFIG_LOCKDEP in the file.
> 
> Use make nconfig and then use f8 to search for CONFIG_LOCKDEP.
> 
> regards,
> dan carpenter

Thanks a lot. As always, you've been very helpful. I appreciate your 
willingness to help and, more generally, your attitude towards people with 
less experience than yours.

By using F8, I found that CONFIG_LOCKDEP is selected by CONFIG_LOCK_STAT (in 
logical AND with other options) but, in my .config, the latter was set to 'n'. 
After setting this other option to 'y', CONFIG_LOCKDEP magically :) appeared  
in .config and it was automatically set to 'y'.

I see that the same kind of search can also be done by using the slash if one 
uses "make menuconfig".

Regards,

Fabio