Smack:- Remove mutex lock "smk_lock" from inode_smack (921bb1cb) · Commits · 戴 / test

"smk_lock" mutex is used during inode instantiation in smack_d_instantiate()function. It has been used to avoid simultaneous access on same inode security structure. Since smack related initialization is done only once i.e during inode creation. If the inode has already been instantiated then smack_d_instantiate() function just returns without doing anything. So it means mutex lock is required only during inode creation. But since 2 processes can't create same inodes or files simultaneously. Also linking or some other file operation can't be done simultaneously when the file is getting created since file lookup will fail before dentry inode linkup which is done after smack initialization. So no mutex lock is required in inode_smack structure. It will save memory as well as improve some performance. If 40000 inodes are created in system, it will save 1.5 MB on 32-bit systems & 2.8 MB on 64-bit systems. Signed-off-by:

Vishal Goel <vishal.goel@samsung.com> Signed-off-by:

Amit Sahrawat <a.sahrawat@samsung.com> Signed-off-by:

Casey Schaufler <casey@schaufler-ca.com>

security/smack/smack.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -109,7 +109,6 @@ struct inode_smack {
		struct smack_known smk_inode; / label of the fso */
		struct smack_known smk_task; / label of the task */
		struct smack_known smk_mmap; / label of the mmap domain */
		struct mutex smk_lock; /* initialization lock */
		int smk_flags; /* smack inode flags */
		};

security/smack/smack_lsm.c

+2 −6

Original line number	Diff line number	Diff line
		@@ -314,7 +314,6 @@ static void init_inode_smack(struct inode inode, struct smack_known skp)

		isp->smk_inode = skp;
		isp->smk_flags = 0;
		mutex_init(&isp->smk_lock);
		}

		/**
		@@ -3264,13 +3263,12 @@ static void smack_d_instantiate(struct dentry opt_dentry, struct inode inode)

		isp = smack_inode(inode);

		mutex_lock(&isp->smk_lock);
		/*
		* If the inode is already instantiated
		* take the quick way out
		*/
		if (isp->smk_flags & SMK_INODE_INSTANT)
		goto unlockandout;
		return;

		sbp = inode->i_sb;
		sbsp = sbp->s_security;
		@@ -3321,7 +3319,7 @@ static void smack_d_instantiate(struct dentry opt_dentry, struct inode inode)
		break;
		}
		isp->smk_flags \|= SMK_INODE_INSTANT;
		goto unlockandout;
		return;
		}

		/*
		@@ -3456,8 +3454,6 @@ static void smack_d_instantiate(struct dentry opt_dentry, struct inode inode)

		isp->smk_flags \|= (SMK_INODE_INSTANT \| transflag);

		unlockandout:
		mutex_unlock(&isp->smk_lock);
		return;
		}

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