diff --git a/Cgroups/cgroups1.md b/Cgroups/cgroups1.md index d5f1312..3c292e8 100644 --- a/Cgroups/cgroups1.md +++ b/Cgroups/cgroups1.md @@ -19,7 +19,7 @@ One `control group subsystem` represents one kind of resources like a processor * `freezer` - allows to suspend/resume for a task(s) from a group; * `net_cls` - allows to mark network packets from task(s) from a group; * `net_prio` - provides a way to dynamically set the priority of network traffic per network interface for a group; -* `perf_event` - provides access to [perf events](https://en.wikipedia.org/wiki/Perf_(Linux)) to a group; +* `perf_event` - provides access to [perf events](https://en.wikipedia.org/wiki/Perf_\(Linux\)) to a group; * `hugetlb` - activates support for [huge pages](https://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt) for a group; * `pid` - sets limit to number of processes in a group. @@ -174,7 +174,7 @@ print line ./cgroup_test_script.sh: line 5: /dev/tty: Operation not permitted ``` -Similar situation will be when you will run you [docker](https://en.wikipedia.org/wiki/Docker_(software)) containers for example: +Similar situation will be when you will run you [docker](https://en.wikipedia.org/wiki/Docker_\(software\)) containers for example: ``` ~$ docker ps @@ -444,6 +444,6 @@ Links * [cgroups kernel documentation](https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt) * [cgroups v2](https://www.kernel.org/doc/Documentation/cgroup-v2.txt) * [bash](https://www.gnu.org/software/bash/) -* [docker](https://en.wikipedia.org/wiki/Docker_(software)) -* [perf events](https://en.wikipedia.org/wiki/Perf_(Linux)) +* [docker](https://en.wikipedia.org/wiki/Docker_\(software\)) +* [perf events](https://en.wikipedia.org/wiki/Perf_\(Linux\)) * [Previous chapter](https://0xax.gitbooks.io/linux-insides/content/MM/linux-mm-1.html) diff --git a/SyncPrim/sync-6.md b/SyncPrim/sync-6.md index 313ee26..b62e45a 100644 --- a/SyncPrim/sync-6.md +++ b/SyncPrim/sync-6.md @@ -4,7 +4,7 @@ Synchronization primitives in the Linux kernel. Part 6. Introduction -------------------------------------------------------------------------------- -This is the sixth part of the chapter which describes [synchronization primitives](https://en.wikipedia.org/wiki/Synchronization_(computer_science)) in the Linux kernel and in the previous parts we finished to consider different [readers-writer lock](https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock) synchronization primitives. We will continue to learn synchronization primitives in this part and start to consider a similar synchronization primitive which can be used to avoid the `writer starvation` problem. The name of this synchronization primitive is - `seqlock` or `sequential locks`. +This is the sixth part of the chapter which describes [synchronization primitives](https://en.wikipedia.org/wiki/Synchronization_\(computer_science\)) in the Linux kernel and in the previous parts we finished to consider different [readers-writer lock](https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock) synchronization primitives. We will continue to learn synchronization primitives in this part and start to consider a similar synchronization primitive which can be used to avoid the `writer starvation` problem. The name of this synchronization primitive is - `seqlock` or `sequential locks`. We know from the previous [part](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-5.html) that [readers-writer lock](https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock) is a special lock mechanism which allows concurrent access for read-only operations, but an exclusive lock is needed for writing or modifying data. As we may guess, it may lead to a problem which is called `writer starvation`. In other words, a writer process can't acquire a lock as long as at least one reader process which acquired a lock holds it. So, in the situation when contention is high, it will lead to situation when a writer process which wants to acquire a lock will wait for it for a long time. @@ -321,7 +321,7 @@ static inline void write_sequnlock_irq(seqlock_t *sl) As we may see, these functions differ only in the initialization of spinlock. They call `spin_lock_irq` and `spin_unlock_irq` instead of `spin_lock` and `spin_unlock`. -Or for example `write_seqlock_irqsave` and `write_sequnlock_irqrestore` functions which are the same but used `spin_lock_irqsave` and `spin_unlock_irqsave` macro to use in [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_(PC_architecture)) handlers. +Or for example `write_seqlock_irqsave` and `write_sequnlock_irqrestore` functions which are the same but used `spin_lock_irqsave` and `spin_unlock_irqsave` macro to use in [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_\(PC_architecture\)) handlers. That's all. @@ -337,7 +337,7 @@ If you have questions or suggestions, feel free to ping me in twitter [0xAX](htt Links -------------------------------------------------------------------------------- -* [synchronization primitives](https://en.wikipedia.org/wiki/Synchronization_(computer_science)) +* [synchronization primitives](https://en.wikipedia.org/wiki/Synchronization_\(computer_science\)) * [readers-writer lock](https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock) * [spinlock](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-1.html) * [critical section](https://en.wikipedia.org/wiki/Critical_section) @@ -348,5 +348,5 @@ Links * [Timers and time management in the Linux kernel](https://0xax.gitbooks.io/linux-insides/content/Timers/) * [interrupt handlers](https://en.wikipedia.org/wiki/Interrupt_handler) * [softirq](https://0xax.gitbooks.io/linux-insides/content/interrupts/interrupts-9.html) -* [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_(PC_architecture)) +* [IRQ](https://en.wikipedia.org/wiki/Interrupt_request_\(PC_architecture\)) * [Previous part](https://0xax.gitbooks.io/linux-insides/content/SyncPrim/sync-5.html) diff --git a/SysCall/syscall-5.md b/SysCall/syscall-5.md index 06433c8..dd8f37d 100644 --- a/SysCall/syscall-5.md +++ b/SysCall/syscall-5.md @@ -216,7 +216,7 @@ At the next step we check that a file is not tried to be opened via [fanotify](h flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC; ``` -We do this to not leak a [file descriptor](https://en.wikipedia.org/wiki/File_descriptor). By default, the new file descriptor is set to remain open across an `execve` system call, but the `open` system call supports `O_CLOEXEC` flag that can be used to change this default behaviour. So we do this to prevent leaking of a file descriptor when one thread opens a file to set `O_CLOEXEC` flag and in the same time the second process does a [fork](https://en.wikipedia.org/wiki/Fork_(system_call)) + [execve](https://en.wikipedia.org/wiki/Exec_(system_call)) and as you may remember that child will have copies of the parent's set of open file descriptors. +We do this to not leak a [file descriptor](https://en.wikipedia.org/wiki/File_descriptor). By default, the new file descriptor is set to remain open across an `execve` system call, but the `open` system call supports `O_CLOEXEC` flag that can be used to change this default behaviour. So we do this to prevent leaking of a file descriptor when one thread opens a file to set `O_CLOEXEC` flag and in the same time the second process does a [fork](https://en.wikipedia.org/wiki/Fork_\(system_call\)) + [execve](https://en.wikipedia.org/wiki/Exec_\(system_call\)) and as you may remember that child will have copies of the parent's set of open file descriptors. At the next step we check that if our flags contains `O_SYNC` flag, we apply `O_DSYNC` flag too: @@ -393,8 +393,8 @@ Links * [x86_64](https://en.wikipedia.org/wiki/X86-64) * [opendir](http://man7.org/linux/man-pages/man3/opendir.3.html) * [fanotify](http://man7.org/linux/man-pages/man7/fanotify.7.html) -* [fork](https://en.wikipedia.org/wiki/Fork_(system_call)) -* [execve](https://en.wikipedia.org/wiki/Exec_(system_call)) +* [fork](https://en.wikipedia.org/wiki/Fork_\(system_call\)) +* [execve](https://en.wikipedia.org/wiki/Exec_\(system_call\)) * [symlink](https://en.wikipedia.org/wiki/Symbolic_link) * [audit](https://linux.die.net/man/8/auditd) * [inode](https://en.wikipedia.org/wiki/Inode)