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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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4ef4ac3601
The routine gets called for every path component during lookup. ->i_mode is going to be cached on account of permission checks, while ->i_rdev is an area which is most likely cache-cold. gcc 14.2 is kind enough to emit one branch: movzwl (%rbx),%eax mov %eax,%edx and $0xb000,%dx cmp $0x2000,%dx je 11bc <inode_permission+0xec> This patch is lazy in that I don't know if the ->i_rdev branch makes any sense with the newly added mode check upfront. I am not changing any semantics here though. Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Link: https://lore.kernel.org/20250416221626.2710239-3-mjguzik@gmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>
69 lines
1.6 KiB
C
69 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/fs.h>
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#define DEVCG_ACC_MKNOD 1
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#define DEVCG_ACC_READ 2
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#define DEVCG_ACC_WRITE 4
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#define DEVCG_ACC_MASK (DEVCG_ACC_MKNOD | DEVCG_ACC_READ | DEVCG_ACC_WRITE)
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#define DEVCG_DEV_BLOCK 1
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#define DEVCG_DEV_CHAR 2
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#define DEVCG_DEV_ALL 4 /* this represents all devices */
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#if defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF)
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int devcgroup_check_permission(short type, u32 major, u32 minor,
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short access);
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static inline int devcgroup_inode_permission(struct inode *inode, int mask)
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{
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short type, access = 0;
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if (likely(!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)))
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return 0;
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if (likely(!inode->i_rdev))
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return 0;
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if (S_ISBLK(inode->i_mode))
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type = DEVCG_DEV_BLOCK;
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else /* S_ISCHR by the test above */
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type = DEVCG_DEV_CHAR;
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if (mask & MAY_WRITE)
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access |= DEVCG_ACC_WRITE;
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if (mask & MAY_READ)
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access |= DEVCG_ACC_READ;
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return devcgroup_check_permission(type, imajor(inode), iminor(inode),
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access);
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}
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static inline int devcgroup_inode_mknod(int mode, dev_t dev)
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{
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short type;
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if (!S_ISBLK(mode) && !S_ISCHR(mode))
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return 0;
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if (S_ISCHR(mode) && dev == WHITEOUT_DEV)
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return 0;
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if (S_ISBLK(mode))
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type = DEVCG_DEV_BLOCK;
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else
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type = DEVCG_DEV_CHAR;
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return devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),
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DEVCG_ACC_MKNOD);
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}
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#else
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static inline int devcgroup_check_permission(short type, u32 major, u32 minor,
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short access)
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{ return 0; }
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static inline int devcgroup_inode_permission(struct inode *inode, int mask)
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{ return 0; }
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static inline int devcgroup_inode_mknod(int mode, dev_t dev)
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{ return 0; }
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#endif
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