June 2015 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Trouble in making an commit .
by Santhosh Pai June 18, 2015

June 18, 2015

Hello Team, I'm trying to make a commit to a checkpatch fix , and i have followed the instructions in the first patch tutorial but i'm not able to commit . Following were the steps done . 1)Made changes to the file 2)Run git diff command got the below output diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 146ab00..02a41bc 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2611,7 +2611,7 @@ static int comedi_open(struct inode *inode, struct file *file) } if (dev->attached && dev->use_count == 0) { if (!try_module_get(dev->driver->module)) { - rc = -ENOSYS; + rc = -ENODATA; goto out; } if (dev->open) { 3) when i run git commit -a i get the below message and the same goes for git commit -s -v bash-4.2$ git commit -a usage: git diff-index [-m] [--cached] [<common diff options>] <tree-ish> [<path>...] common diff options: -z output diff-raw with lines terminated with NUL. -p output patch format. -u synonym for -p. --patch-with-raw output both a patch and the diff-raw format. --stat show diffstat instead of patch. --numstat show numeric diffstat instead of patch. --patch-with-stat output a patch and prepend its diffstat. --name-only show only names of changed files. --name-status show names and status of changed files. --full-index show full object name on index lines. --abbrev=<n> abbreviate object names in diff-tree header and diff-raw. -R swap input file pairs. -B detect complete rewrites. -M detect renames. -C detect copies. --find-copies-harder try unchanged files as candidate for copy detection. -l<n> limit rename attempts up to <n> paths. -O<file> reorder diffs according to the <file>. -S<string> find filepair whose only one side contains the string. --pickaxe-all show all files diff when -S is used and hit is found. -a --text treat all files as text. i'm not able to commit the changes ,let us know what could be the problem . Below is the details of the git version git version 1.7.11.7OS : Fedora Regards, Santosh Pai

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Qemu configuration question
by Sébastien Hinderer June 18, 2015

June 18, 2015

Dear all, When running my configured kernel in Qemu, poweroff does not work properly: the machine is halted but the kvm process that runs it does not terminate, whereas it does so when powering off the machine after having booted a regular Debian kernel. Current kernel configuration: http://paste.debian.net/233958/ Can anobody see what's missing or misconfigured? Thanks! Sébastien.

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回复：Re: 回复：Re: what the difference between esp and esp0?
by hitmoon June 17, 2015

June 17, 2015

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why use while(0) to write set_current_state
by 慕冬亮 June 17, 2015

June 17, 2015

I see the macro in the include/linux/sched.h #define __set_current_state(state_value) \ do { current->state = (state_value); } while (0) Why define it like this? What's the meaning of while? mudongliang

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回复：Re: 回复：Re: what the difference between esp and esp0?
by hitmoon June 17, 2015

June 17, 2015

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what the difference between esp and esp0?
by hitmoon June 17, 2015

June 17, 2015

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Android Kernel
by Leng Xuedong June 16, 2015

June 16, 2015

Dear All, It is a question about Android Kernel. Do you know how does Android mount devices in /dev ? I found something like chmod 0660 /dev/pn547 in the /init.rc file. but actually, there is no /dev/pn547 . I want to know how can I mount or find the device called pn547.

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Kernel contributions from organisations and individual privacy
by Chris Packham June 16, 2015

June 16, 2015

Hi, This came up at work today and I'm not sure where the best place to ask is. I almost went straight to the lkml but I figured I'd start with newbies first. We've been using the Linux kernel in our products for a number of years now. We're doing all the right things w.r.t GPL compliance but we're not actively pushing that much upstream. This means we're effectively maintaining our own Linux fork with very few resources. I'm trying to avoid this by encouraging developers to get their changes upstreamed. This is good for our organisation because we don't have to re-do our changes when we need to take a new kernel version. Most developers see this as a good career building for them. But some developers value their individual privacy over career progression. My initial response to that was well we can just make a dummy gmail account or even setup a swdept@$organisation shared address. But SubmittingPatches actually says to sign patches with your real name not a pseudonym. Does this basically mean people that value privacy are unable to contribute? Thanks, Chris

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Kernel gets deadlocked during smp booting
by AYAN KUMAR HALDER June 16, 2015

June 16, 2015

Hi All, I am booting kernel 4.0.4 on an ARM based custom SOC with SMP enabled. I see that the kernel gets deadlocked on a spinlock. To be precise, static inline void arch_spin_lock(arch_spinlock_t *lock) { ... // loops in the following while loop for indefinite period while (lockval.tickets.next != lockval.tickets.owner) { wfe(); lockval.tickets.owner = ACCESS_ONCE(lock->tickets.owner); } } Can someone explain to me what does the loop exactly do. Besides, any pointers about how to debug such issues. The backtrace shows the following:- arch_spin_lock _raw_spin_lock vprintk_emit ----> raw_spin_lock(&logbuf_lock); vprintk_default printk smp_init I can guess that the deadlock is being caused due to logbuf_lock. But, I am unable to proceed further. Thanks and Regards, Ayan kumar Halder

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Change proc/<pid>/cmdline to 8k
by Navin P June 16, 2015

June 16, 2015

Hi, I want to change the cmdline of a process to support 8096 . It works well on ppc where the page size is 65k. But when i try to increase it on x86 (i686) http://lxr.free-electrons.com/source/fs/proc/base.c by doing 6*PAGE_SIZE, i get kernel panic after some time 199 static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns, 200 struct pid *pid, struct task_struct *task) 201 { 202 /* 203 * Rely on struct seq_operations::show() being called once 204 * per internal buffer allocation. See single_open(), traverse(). 205 */ 206 BUG_ON(m->size < PAGE_SIZE); 207 m->count += get_cmdline(task, m->buf, 6*PAGE_SIZE); 208 return 0; 209 } 210 Regards, Navin

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